Fix watch history sync for logged-in users without NIP-04 permissions.

Updates `shouldUseExtensionForHistory` in `js/watchHistoryService.js` to check for `signEvent` instead of `nip04.decrypt`. This ensures that logged-in users can sync their watch history (which is now plaintext) even if they haven't granted the legacy encryption permission.

js/watchHistoryService.js

@@ -108,11 +108,11 @@ function shouldUseExtensionForHistory(actorKey) {
   }
 
   const extension = window.nostr;
-  if (!extension || !extension.nip04) {
+  if (!extension) {
     return false;
   }
 
-  return typeof extension.nip04.decrypt === "function";
+  return typeof extension.signEvent === "function";
 }
 
 async function ensureWatchHistoryExtensionPermissions(actorKey) {