fix(panel): keep WebSocket alive across route transitions

Disconnecting and reconnecting the WebSocket on every route change caused
a race condition: the old socket's async onclose handler would null out
globalWs after the new socket was created, causing JOIN_ROOM messages to
be silently dropped. The WebSocket is a global singleton — keep it alive
and let the built-in reconnection logic handle actual disconnects.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

panel/src/lib/useWebSocket.ts

@@ -1,4 +1,4 @@
-import { useEffect, useRef, useCallback, useState } from "react";
+import { useEffect, useCallback, useState } from "react";
 
 type MessageHandler = (data: any) => void;
 
@@ -50,23 +50,11 @@ function connect(): void {
     globalWs = ws;
 }
 
-function disconnect(): void {
-    if (reconnectTimer) {
-        clearTimeout(reconnectTimer);
-        reconnectTimer = null;
-    }
-    globalWs?.close();
-    globalWs = null;
-    globalConnected = false;
-}
-
 export function useWebSocket() {
     const [connected, setConnected] = useState(globalConnected);
-    const refCount = useRef(0);
 
     useEffect(() => {
-        refCount.current++;
-        if (refCount.current === 1 && !globalWs) {
+        if (!globalWs) {
             connect();
         }
 
@@ -78,10 +66,6 @@ export function useWebSocket() {
 
         return () => {
             globalHandlers.delete(handler);
-            refCount.current--;
-            if (refCount.current === 0) {
-                disconnect();
-            }
         };
     }, []);