fix: use host outbox relays for NIP-53 live chat events

Combine activity relays, naddr hints, and host's outbox relays when
subscribing to chat messages and zaps. This ensures events are fetched
from all relevant sources where they may be published.

src/lib/chat/adapters/nip-53-adapter.ts

@@ -175,9 +175,10 @@ export class Nip53Adapter extends ChatProtocolAdapter {
       participants.unshift({ pubkey: hostPubkey, role: "host" });
     }
 
-    // Determine relays for chat - prefer activity's relays tag, fallback to relay hints
-    const chatRelays =
-      activity.relays.length > 0 ? activity.relays : relayHints;
+    // Combine activity relays, relay hints, and host outboxes for comprehensive coverage
+    const chatRelays = [
+      ...new Set([...activity.relays, ...relayHints, ...authorOutboxes]),
+    ];
 
     console.log(
       `[NIP-53] Resolved: "${activity.title}" (${status}), ${participants.length} participants, ${chatRelays.length} relays`,