fix: properly clear wallet state on disconnect and update copy

Changes:
- Clear all wallet state when disconnecting (transactions, walletInfo, loading flags)
- Previously only cleared state on connect, leaving stale data visible
- Remove "Mutiny" mention from connection dialog copy
- Update to generic "NWC wallet provider" text

Now when you disconnect the wallet with the window open, it properly
clears all data and returns to the "No Wallet Connected" state.

src/components/ConnectWalletDialog.tsx

@@ -129,8 +129,8 @@ export default function ConnectWalletDialog({
 
         <div className="space-y-4">
           <p className="text-sm text-muted-foreground">
-            Enter your wallet connection string. You can get this from your
-            wallet provider (Alby, Mutiny, etc.)
+            Enter your wallet connection string. You can get this from your NWC
+            wallet provider.
           </p>
 
           {error && (

src/components/WalletViewer.tsx

@@ -252,6 +252,15 @@ export default function WalletViewer() {
         setTxLoadFailed(false);
         setTransactions([]);
         setWalletInfo(null);
+      } else {
+        // Clear all state when wallet disconnects
+        setTxLoadAttempted(false);
+        setTxLoadFailed(false);
+        setTransactions([]);
+        setWalletInfo(null);
+        setLoading(false);
+        setLoadingMore(false);
+        setHasMore(true);
       }
     }