feat: auto-close ZapWindow after successful wallet payment

Changes:
- Add onClose callback prop to ZapWindowProps interface
- Pass onClose from WindowRenderer to ZapWindow component
- Call onClose() with 1.5s delay after successful wallet payment
- Allow user to see success toast before window closes

User Experience:
- After zapping with wallet, window automatically closes
- 1.5 second delay allows user to see success message
- Prevents accidental double-zapping
- Cleaner flow - no manual window closing needed

Implementation:
- WindowRenderer passes onClose callback to ZapWindow
- ZapWindow calls onClose after payment success and toasts
- setTimeout(onClose, 1500) provides brief delay for UX
- QR code path unchanged (window stays open for payment)

All tests passing (939 passed)
Build successful

src/components/WindowRenderer.tsx

@@ -234,6 +234,7 @@ export function WindowRenderer({ window, onClose }: WindowRendererProps) {
           <ZapWindow
             recipientPubkey={window.props.recipientPubkey}
             eventPointer={window.props.eventPointer}
+            onClose={onClose}
           />
         );
         break;

src/components/ZapWindow.tsx

@@ -54,6 +54,8 @@ export interface ZapWindowProps {
   recipientPubkey: string;
   /** Optional event being zapped (adds context) */
   eventPointer?: EventPointer | AddressPointer;
+  /** Callback to close the window */
+  onClose?: () => void;
 }
 
 // Default preset amounts in sats
@@ -79,6 +81,7 @@ function formatAmount(amount: number): string {
 export function ZapWindow({
   recipientPubkey: initialRecipientPubkey,
   eventPointer,
+  onClose,
 }: ZapWindowProps) {
   // Load event if we have a pointer and no recipient pubkey (derive from event author)
   const event = use$(() => {
@@ -345,6 +348,12 @@ export function ZapWindow({
         if (invoiceResponse.successAction?.message) {
           toast.info(invoiceResponse.successAction.message);
         }
+
+        // Close the window after successful zap
+        if (onClose) {
+          // Small delay to let the user see the success toast
+          setTimeout(() => onClose(), 1500);
+        }
       } else {
         // Show QR code and invoice
         const qrUrl = await generateQrCode(invoiceText);