perf Optimize Socket Emits Using User Rooms (#18996)

* This PR optimizes socket delta event broadcasting by leveraging rooms. Instead of iterating through a user's sessions and emitting events individually, this change sends a single event to a user-specific room. This approach is more efficient, reducing overhead and improving performance, particularly for users with multiple concurrent sessions.

In testing this dramatically reduces emits and server load.

* Update main.py

Added userroom join

---------

Co-authored-by: Tim Baek <tim@openwebui.com>

backend/open_webui/socket/main.py

@@ -282,6 +282,7 @@ async def connect(sid, environ, auth):
             else:
                 USER_POOL[user.id] = [sid]
 
+            await sio.enter_room(sid, f"user:{user.id}")
 
 @sio.on("user-join")
 async def user_join(sid, data):
@@ -304,6 +305,7 @@ async def user_join(sid, data):
     else:
         USER_POOL[user.id] = [sid]
 
+    await sio.enter_room(sid, f"user:{user.id}")
     # Join all the channels
     channels = Channels.get_channels_by_user_id(user.id)
     log.debug(f"{channels=}")
@@ -650,34 +652,18 @@ def get_event_emitter(request_info, update_db=True):
     async def __event_emitter__(event_data):
         user_id = request_info["user_id"]
 
-        session_ids = list(
-            set(
-                USER_POOL.get(user_id, [])
-                + (
-                    [request_info.get("session_id")]
-                    if request_info.get("session_id")
-                    else []
-                )
-            )
-        )
-
         chat_id = request_info.get("chat_id", None)
         message_id = request_info.get("message_id", None)
 
-        emit_tasks = [
-            sio.emit(
-                "events",
-                {
-                    "chat_id": chat_id,
-                    "message_id": message_id,
-                    "data": event_data,
-                },
-                to=session_id,
-            )
-            for session_id in session_ids
-        ]
-
-        await asyncio.gather(*emit_tasks)
+        await sio.emit(
+            "events",
+            {
+                "chat_id": chat_id,
+                "message_id": message_id,
+                "data": event_data,
+            },
+            room=f"user:{user_id}",
+        )
         if (
             update_db
             and message_id