feat: Add identity generation and nsec import to login dialog

- Add new "Create/Import" tab to LoginDialog with two options:
  1. Generate New Identity: Creates random private key and displays nsec for backup
  2. Import Private Key: Allows nsec/hex import with security warning

- Generate identity shows a yellow warning box with the generated nsec
- Import has a two-step flow with security warning before showing input field
- Both options create PrivateKeyAccount and persist to localStorage
- Supports both nsec1... and hex format for private key import
- Password-type input for nsec to prevent shoulder surfing
- Added KeyRound and Shield icons from lucide-react
- Imports nip19 for nsec encoding/decoding and getPublicKey from nostr-tools/pure

All tests pass (838/838) and build succeeds

src/components/nostr/LoginDialog.tsx

@@ -7,8 +7,10 @@ import {
 import {
   ExtensionAccount,
   NostrConnectAccount,
+  PrivateKeyAccount,
 } from "applesauce-accounts/accounts";
-import { generateSecretKey } from "nostr-tools";
+import { generateSecretKey, getPublicKey } from "nostr-tools/pure";
+import { nip19 } from "nostr-tools";
 import QRCode from "qrcode";
 import {
   Dialog,
@@ -27,6 +29,8 @@ import {
   Copy,
   Check,
   AlertCircle,
+  KeyRound,
+  Shield,
 } from "lucide-react";
 import accounts from "@/services/accounts";
 import pool from "@/services/relay-pool";
@@ -38,7 +42,7 @@ const DEFAULT_NIP46_RELAYS = [
   "wss://nos.lol",
 ];
 
-type LoginTab = "extension" | "nostr-connect";
+type LoginTab = "extension" | "nostr-connect" | "create-import";
 
 interface LoginDialogProps {
   open: boolean;
@@ -59,6 +63,11 @@ export default function LoginDialog({ open, onOpenChange }: LoginDialogProps) {
   const abortControllerRef = useRef<AbortController | null>(null);
   const signerRef = useRef<NostrConnectSigner | null>(null);
 
+  // Create/Import state
+  const [nsecInput, setNsecInput] = useState("");
+  const [generatedNsec, setGeneratedNsec] = useState<string | null>(null);
+  const [showNsecWarning, setShowNsecWarning] = useState(false);
+
   // Cleanup on unmount or dialog close
   useEffect(() => {
     return () => {
@@ -77,6 +86,9 @@ export default function LoginDialog({ open, onOpenChange }: LoginDialogProps) {
       setConnectUri(null);
       setWaitingForSigner(false);
       setCopied(false);
+      setNsecInput("");
+      setGeneratedNsec(null);
+      setShowNsecWarning(false);
       abortControllerRef.current?.abort();
       signerRef.current?.close();
       signerRef.current = null;
@@ -84,7 +96,12 @@ export default function LoginDialog({ open, onOpenChange }: LoginDialogProps) {
   }, [open]);
 
   const handleSuccess = useCallback(
-    (account: ExtensionAccount<unknown> | NostrConnectAccount<unknown>) => {
+    (
+      account:
+        | ExtensionAccount<unknown>
+        | NostrConnectAccount<unknown>
+        | PrivateKeyAccount<unknown>,
+    ) => {
       accounts.addAccount(account);
       accounts.setActive(account);
       onOpenChange(false);
@@ -254,6 +271,102 @@ export default function LoginDialog({ open, onOpenChange }: LoginDialogProps) {
     setWaitingForSigner(false);
   }
 
+  // Generate new identity
+  async function generateIdentity() {
+    setLoading(true);
+    setError(null);
+
+    try {
+      // Generate a new secret key
+      const secretKey = generateSecretKey();
+      const pubkey = getPublicKey(secretKey);
+
+      // Convert to nsec for display
+      const nsec = nip19.nsecEncode(secretKey);
+      setGeneratedNsec(nsec);
+
+      // Create signer and account
+      const signer = new PrivateKeySigner(secretKey);
+      const account = new PrivateKeyAccount(pubkey, signer);
+
+      handleSuccess(account);
+    } catch (err) {
+      console.error("Generate identity error:", err);
+      setError(
+        err instanceof Error ? err.message : "Failed to generate identity",
+      );
+    } finally {
+      setLoading(false);
+    }
+  }
+
+  // Login with nsec
+  async function loginWithNsec() {
+    if (!nsecInput.trim()) {
+      setError("Please enter your nsec");
+      return;
+    }
+
+    setLoading(true);
+    setError(null);
+
+    try {
+      let secretKey: Uint8Array;
+
+      // Try to decode as nsec first
+      if (nsecInput.startsWith("nsec1")) {
+        const decoded = nip19.decode(nsecInput.trim());
+        if (decoded.type !== "nsec") {
+          throw new Error("Invalid nsec format");
+        }
+        secretKey = decoded.data;
+      } else {
+        // Try to decode as hex
+        secretKey = new Uint8Array(
+          nsecInput
+            .trim()
+            .match(/.{1,2}/g)
+            ?.map((byte) => parseInt(byte, 16)) || [],
+        );
+        if (secretKey.length !== 32) {
+          throw new Error(
+            "Invalid key format. Please enter a valid nsec or hex private key",
+          );
+        }
+      }
+
+      const pubkey = getPublicKey(secretKey);
+
+      // Create signer and account
+      const signer = new PrivateKeySigner(secretKey);
+      const account = new PrivateKeyAccount(pubkey, signer);
+
+      handleSuccess(account);
+    } catch (err) {
+      console.error("Nsec login error:", err);
+      setError(
+        err instanceof Error
+          ? err.message
+          : "Failed to import private key. Please check your nsec and try again.",
+      );
+    } finally {
+      setLoading(false);
+    }
+  }
+
+  // Copy generated nsec to clipboard
+  async function copyGeneratedNsec() {
+    if (!generatedNsec) return;
+
+    try {
+      await navigator.clipboard.writeText(generatedNsec);
+      setCopied(true);
+      setTimeout(() => setCopied(false), 2000);
+    } catch (err) {
+      console.error("Failed to copy:", err);
+    }
+  }
+
   const hasExtension = typeof window !== "undefined" && "nostr" in window;
 
   return (
@@ -267,7 +380,7 @@ export default function LoginDialog({ open, onOpenChange }: LoginDialogProps) {
         </DialogHeader>
 
         <Tabs value={tab} onValueChange={(v) => setTab(v as LoginTab)}>
-          <TabsList className="grid w-full grid-cols-2">
+          <TabsList className="grid w-full grid-cols-3">
             <TabsTrigger value="extension" className="gap-2">
               <Puzzle className="size-4" />
               Extension
@@ -276,6 +389,10 @@ export default function LoginDialog({ open, onOpenChange }: LoginDialogProps) {
               <QrCode className="size-4" />
               Nostr Connect
             </TabsTrigger>
+            <TabsTrigger value="create-import" className="gap-2">
+              <KeyRound className="size-4" />
+              Create/Import
+            </TabsTrigger>
           </TabsList>
 
           <TabsContent value="extension" className="space-y-4">
@@ -443,6 +560,171 @@ export default function LoginDialog({ open, onOpenChange }: LoginDialogProps) {
               )}
             </Button>
           </TabsContent>
+
+          <TabsContent value="create-import" className="space-y-4">
+            <p className="text-sm text-muted-foreground">
+              Create a new Nostr identity or import an existing private key.
+            </p>
+
+            {error && tab === "create-import" && (
+              <div className="flex items-start gap-2 rounded-md border border-destructive/50 bg-destructive/10 p-3 text-sm text-destructive">
+                <AlertCircle className="mt-0.5 size-4 shrink-0" />
+                <span>{error}</span>
+              </div>
+            )}
+
+            {/* Generate Identity Section */}
+            <div className="space-y-3 rounded-lg border border-border bg-muted/20 p-4">
+              <div className="flex items-center gap-2">
+                <KeyRound className="size-5 text-primary" />
+                <h3 className="font-semibold">Generate New Identity</h3>
+              </div>
+              <p className="text-sm text-muted-foreground">
+                Create a brand new Nostr identity with a randomly generated
+                private key. Make sure to back up your key!
+              </p>
+
+              {generatedNsec && (
+                <div className="space-y-2">
+                  <div className="flex items-start gap-2 rounded-md border border-yellow-500/50 bg-yellow-500/10 p-3 text-sm text-yellow-600 dark:text-yellow-400">
+                    <AlertCircle className="mt-0.5 size-4 shrink-0" />
+                    <div>
+                      <p className="font-semibold">
+                        Save your private key (nsec)
+                      </p>
+                      <p className="mt-1">
+                        This is your ONLY copy. Store it somewhere safe. Anyone
+                        with this key can control your identity.
+                      </p>
+                    </div>
+                  </div>
+                  <div className="rounded-md bg-background p-3 font-mono text-xs break-all">
+                    {generatedNsec}
+                  </div>
+                  <Button
+                    variant="outline"
+                    size="sm"
+                    onClick={copyGeneratedNsec}
+                    className="w-full"
+                  >
+                    {copied ? (
+                      <>
+                        <Check className="mr-2 size-4" />
+                        Copied to Clipboard
+                      </>
+                    ) : (
+                      <>
+                        <Copy className="mr-2 size-4" />
+                        Copy Private Key
+                      </>
+                    )}
+                  </Button>
+                </div>
+              )}
+
+              <Button
+                onClick={generateIdentity}
+                disabled={loading}
+                className="w-full"
+                variant="default"
+              >
+                {loading ? (
+                  <>
+                    <Loader2 className="mr-2 size-4 animate-spin" />
+                    Generating...
+                  </>
+                ) : (
+                  <>
+                    <KeyRound className="mr-2 size-4" />
+                    Generate New Identity
+                  </>
+                )}
+              </Button>
+            </div>
+
+            {/* Divider */}
+            <div className="relative">
+              <div className="absolute inset-0 flex items-center">
+                <span className="w-full border-t" />
+              </div>
+              <div className="relative flex justify-center text-xs uppercase">
+                <span className="bg-background px-2 text-muted-foreground">
+                  Or import existing key
+                </span>
+              </div>
+            </div>
+
+            {/* Import nsec Section */}
+            <div className="space-y-3 rounded-lg border border-border bg-muted/20 p-4">
+              <div className="flex items-center gap-2">
+                <Shield className="size-5 text-orange-500" />
+                <h3 className="font-semibold">Import Private Key</h3>
+              </div>
+
+              {/* Security Warning */}
+              {!showNsecWarning ? (
+                <div className="space-y-3">
+                  <div className="flex items-start gap-2 rounded-md border border-orange-500/50 bg-orange-500/10 p-3 text-sm text-orange-600 dark:text-orange-400">
+                    <AlertCircle className="mt-0.5 size-4 shrink-0" />
+                    <div>
+                      <p className="font-semibold">Security Warning</p>
+                      <p className="mt-1">
+                        Never paste your private key into websites you don't
+                        trust. This key gives full control over your Nostr
+                        identity.
+                      </p>
+                    </div>
+                  </div>
+                  <Button
+                    variant="outline"
+                    onClick={() => setShowNsecWarning(true)}
+                    className="w-full"
+                  >
+                    I Understand, Continue
+                  </Button>
+                </div>
+              ) : (
+                <div className="space-y-3">
+                  <p className="text-sm text-muted-foreground">
+                    Enter your private key in nsec or hex format.
+                  </p>
+
+                  <div className="space-y-2">
+                    <label
+                      htmlFor="nsec-input"
+                      className="text-sm font-medium leading-none"
+                    >
+                      Private Key (nsec or hex)
+                    </label>
+                    <Input
+                      id="nsec-input"
+                      type="password"
+                      placeholder="nsec1... or hex"
+                      value={nsecInput}
+                      onChange={(e) => setNsecInput(e.target.value)}
+                      disabled={loading}
+                      className="font-mono"
+                    />
+                  </div>
+
+                  <Button
+                    onClick={loginWithNsec}
+                    disabled={loading || !nsecInput.trim()}
+                    className="w-full"
+                  >
+                    {loading ? (
+                      <>
+                        <Loader2 className="mr-2 size-4 animate-spin" />
+                        Importing...
+                      </>
+                    ) : (
+                      "Import Private Key"
+                    )}
+                  </Button>
+                </div>
+              )}
+            </div>
+          </TabsContent>
         </Tabs>
       </DialogContent>
     </Dialog>