fix(ws): idempotent connection removal, release slot on any error

The status WebSocket pool removed connections with list.remove(), which
raises ValueError on a double-remove (broadcast already dropped a dead
socket, then disconnect tries again), and only released a slot on
WebSocketDisconnect — any other error leaked the socket into the
broadcast pool. Centralise removal in an idempotent _drop() called from
a finally block and from _broadcast.

ha-relevant: yes

backend/app/api/routes/status.py

@@ -1,3 +1,4 @@
+import contextlib
 import json
 
 from fastapi import APIRouter, WebSocket, WebSocketDisconnect
@@ -10,6 +11,12 @@ router = APIRouter()
 _connections: list[WebSocket] = []
 
 
+def _drop(websocket: WebSocket) -> None:
+    """Remove a connection if still present — idempotent, never raises."""
+    with contextlib.suppress(ValueError):
+        _connections.remove(websocket)
+
+
 @router.websocket("/ws/status")
 async def ws_status(websocket: WebSocket) -> None:
     # Accept first so we can send a close frame with a reason code
@@ -33,7 +40,11 @@ async def ws_status(websocket: WebSocket) -> None:
         while True:
             await websocket.receive_text()
     except WebSocketDisconnect:
-        _connections.remove(websocket)
+        pass
+    finally:
+        # Any error (disconnect or otherwise) must release the slot, else the
+        # dead socket lingers in the broadcast pool.
+        _drop(websocket)
 
 
 async def _broadcast(payload: str) -> None:
@@ -41,7 +52,7 @@ async def _broadcast(payload: str) -> None:
         try:
             await conn.send_text(payload)
         except Exception:
-            _connections.remove(conn)
+            _drop(conn)
 
 
 async def broadcast_status(node_id: str, status: str, checked_at: str, response_time_ms: int | None = None) -> None: