Increase mention fetch timeout and retry on empty

Tag-based #p queries are slower on some relays. Increase timeout
from 8s to 12s for fetchMentions. Also retry once after 3s if the
initial notification fetch returns empty (helps on cold start when
relays need time to connect).

src/lib/nostr/social.ts

@@ -74,10 +74,11 @@ export async function fetchFollowSuggestions(myFollows: string[]): Promise<{ pub
 
 export async function fetchMentions(pubkey: string, since: number, limit = 50): Promise<NDKEvent[]> {
   const instance = getNDK();
+  // Use a longer timeout for #p queries — some relays are slow to index tag lookups
   const events = await fetchWithTimeout(
     instance,
     { kinds: [NDKKind.Text], "#p": [pubkey], since, limit },
-    FEED_TIMEOUT,
+    12000,
   );
   return Array.from(events).sort((a, b) => (b.created_at ?? 0) - (a.created_at ?? 0));
 }