fix: Fix users unable to see or hear each other in voice channels due to

stale server sockets, passive non-initiators, and race conditions
during peer connection setup.

Fix users unable to see or hear each other in voice channels due to
stale server sockets, passive non-initiators, and race conditions
during peer connection setup.

Server:
- Close stale WebSocket connections sharing the same oderId in
  handleIdentify instead of letting them linger up to 45s
- Make user_joined/user_left broadcasts identity-aware so duplicate
  sockets don't produce phantom join/leave events
- Include serverIds in user_left payload for multi-room presence
- Simplify findUserByOderId now that stale sockets are cleaned up

Client - signaling:
- Add fallback offer system with 1s timer for missed user_joined races
- Add non-initiator takeover after 5s when the initiator fails to send
  an offer (NON_INITIATOR_GIVE_UP_MS)
- Scope peerServerMap per signaling URL to prevent cross-server
  collisions
- Add socket identity guards on all signaling event handlers
- Replace canReusePeerConnection with hasActivePeerConnection and
  isPeerConnectionNegotiating with extended grace periods

Client - peer connections:
- Extract replaceUnusablePeer helper to deduplicate stale peer
  replacement in offer and ICE handlers
- Add stale connectionstatechange guard to ignore events from replaced
  RTCPeerConnection instances
- Use deterministic initiator election in peer recovery reconnects
- Track createdAt on PeerData for staleness detection

Client - presence:
- Add multi-room presence tracking via presenceServerIds on User
- Replace clearUsers + individual userJoined with syncServerPresence
  for atomic server roster updates
- Make userLeft handle partial server removal instead of full eviction

Documentation:
- Add server-side connection hygiene, non-initiator takeover, and stale
  peer replacement sections to the realtime README

toju-app/src/app/store/users/users.actions.ts

@@ -29,7 +29,8 @@ export const UsersActions = createActionGroup({
     'Load Room Users Failure': props<{ error: string }>(),
 
     'User Joined': props<{ user: User }>(),
-    'User Left': props<{ userId: string }>(),
+    'User Left': props<{ userId: string; serverId?: string; serverIds?: string[] }>(),
+    'Sync Server Presence': props<{ roomId: string; users: User[] }>(),
 
     'Update User': props<{ userId: string; updates: Partial<User> }>(),
     'Update User Role': props<{ userId: string; role: User['role'] }>(),