feat: signal server tag

toju-app/src/app/store/rooms/rooms.effects.ts

@@ -149,6 +149,26 @@ export class RoomsEffects {
     )
   );
 
+  /** Re-joins saved rooms after the signaling socket reconnects so presence is restored. */
+  resyncRoomsOnSignalingReconnect$ = createEffect(
+    () =>
+      this.webrtc.signalingReconnected$.pipe(
+        withLatestFrom(
+          this.store.select(selectCurrentUser),
+          this.store.select(selectCurrentRoom),
+          this.store.select(selectSavedRooms)
+        ),
+        tap(([
+          , user,
+          currentRoom,
+          savedRooms
+        ]) => {
+          this.signalingConnection.syncSavedRoomConnections(user ?? null, currentRoom, savedRooms, this.router.url);
+        })
+      ),
+    { dispatch: false }
+  );
+
   /** Reconnects saved rooms so joined servers stay online while the app is running. */
   keepSavedRoomsConnected$ = createEffect(
     () =>