fix(room): fix two major memory leaks

1. WS disconnect now unsubscribes from user_notification_inner.
   Previously, every WebSocket connection created a broadcast channel
   for user notifications that was never removed on disconnect, causing
   unbounded growth proportional to unique connected users over time.

2. Room worker tasks now use the manager's room_shutdown_txs channel
   instead of a local broadcast channel. shutdown_room() sends on this
   channel, so when a room is deleted the worker task receives the signal
   and terminates, releasing its DashMap (capacity 10,000) and all
   captured closures. Previously the worker ran forever.

libs/api/room/ws_universal.rs

@@ -445,6 +445,7 @@ pub async fn ws_universal(
         for room_id in push_streams.keys() {
             manager.unsubscribe(*room_id, user_id).await;
         }
+        manager.unsubscribe_user_notification(user_id).await;
         manager.metrics.ws_connections_active.decrement(1.0);
         manager.metrics.ws_disconnections_total.increment(1);
     });

libs/room/src/service/workers.rs

@@ -270,19 +270,21 @@ pub fn spawn_room_workers(
     );
     let get_redis: Arc<dyn Fn() -> queue::worker::RedisFuture + Send + Sync> =
         extract_get_redis(queue.clone());
-    let manager = room_manager.clone();
-    let redis_url_clone = redis_url.clone();
-    let semaphore = worker_semaphore.clone();
-
+    let manager1 = room_manager.clone();
     let manager2 = room_manager.clone();
+    let manager3 = room_manager.clone();
+    let redis_url_clone = redis_url.clone();
     let redis_url3 = redis_url.clone();
+    let semaphore = worker_semaphore.clone();
 
     tokio::spawn(async move {
         let _permit = match semaphore.acquire_owned().await {
             Ok(p) => p,
             Err(_) => return,
         };
-        let (shutdown_tx, shutdown_rx) = tokio::sync::broadcast::channel::<()>(1);
+        // Use the manager's room shutdown channel so the worker terminates
+        // when the room is deleted (shutdown_room sends on room_shutdown_txs).
+        let shutdown_rx = manager1.register_room(room_id).await;
         queue::room_worker_task(
             room_id,
             uuid::Uuid::new_v4().to_string(),
@@ -291,14 +293,13 @@ pub fn spawn_room_workers(
             shutdown_rx,
         )
         .await;
-        let _ = shutdown_tx.send(());
     });
 
     tokio::spawn(async move {
-        let shutdown_rx = manager.register_room(room_id).await;
+        let shutdown_rx = manager2.register_room(room_id).await;
         crate::connection::subscribe_room_events(
             redis_url_clone,
-            manager.clone(),
+            manager2,
             room_id,
             shutdown_rx,
         )
@@ -317,10 +318,10 @@ pub fn spawn_room_workers(
                 None => return,
             }
         };
-        let shutdown_rx = manager2.register_project(project_id).await;
+        let shutdown_rx = manager3.register_project(project_id).await;
         crate::connection::subscribe_project_room_events(
             redis_url3,
-            manager2,
+            manager3,
             project_id,
             shutdown_rx,
         )