feat(federation): queue S2S presence_update on auth/disconnect/status/activity changes

New FederationPresenceUpdatePayload + queuePresenceRelay() helper. Five WS
sites now project the native user's status (and optional activities) to all
active peers via the outbox: WS auth-success, finalizeDisconnect,
manual presence_update, activity_update, showActivity-toggle clear.

Outbox-only (no mutation-log entry) — presence is ephemeral; the upcoming
peer-activation hook re-emits a fresh snapshot so peers recovering from
unreachable converge without history replay. No-op for replicated users.

packages/server/src/ws/handler.ts

@@ -307,6 +307,12 @@ class ConnectionManager {
       });
     }
 
+    // S2S: project offline to all active peers (mirrors profile_update fanout).
+    // Imported lazily to avoid circular import (federationPresence → db → ws/handler).
+    void import('../utils/federationPresence.js').then(({ queuePresenceRelay }) => {
+      try { queuePresenceRelay(userId, 'offline', []); } catch (e) { console.warn('[ws] queuePresenceRelay(offline) failed', e); }
+    });
+
     // Clean up userSpaces (re-populated on next connect via setUserSpaces)
     this.userSpaces.delete(userId);
 
@@ -1672,6 +1678,12 @@ export async function registerWebSocket(app: FastifyInstance): Promise<void> {
               status: 'online',
             }, userId);
           }
+
+          // S2S: project online to all active peers (mirrors profile_update fanout).
+          const _uid = userId;
+          void import('../utils/federationPresence.js').then(({ queuePresenceRelay }) => {
+            try { queuePresenceRelay(_uid, 'online', []); } catch (e) { console.warn('[ws] queuePresenceRelay(online) failed', e); }
+          });
         } catch {
           ws.send(JSON.stringify({ type: 'error', message: 'Invalid token' }));
           ws.close();