Fix profile cache invalidation after editing

Invalidate the in-memory profile cache for the user's pubkey after
publishing a new kind 0 event, so the updated profile reflects immediately.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/hooks/useProfile.ts

@@ -4,6 +4,11 @@ import { fetchProfile } from "../lib/nostr";
 const profileCache = new Map<string, any>();
 const pendingRequests = new Map<string, Promise<any>>();
 
+export function invalidateProfileCache(pubkey: string) {
+  profileCache.delete(pubkey);
+  pendingRequests.delete(pubkey);
+}
+
 export function useProfile(pubkey: string) {
   const [profile, setProfile] = useState<any>(profileCache.get(pubkey) ?? null);