fix(socket): improve connection stability with heartbeat and auto-reconnect

- Backend: Add pingInterval (25s) and pingTimeout (60s) for better keep-alive
- Frontend: Increase reconnection attempts to Infinity (keep trying forever)
- Frontend: Add reconnect event handlers to rejoin rooms after reconnection
- Frontend: Check initial connection state when reusing socket instance

frontend/src/services/socket.js

@@ -26,9 +26,17 @@ export function connectSocket() {
     auth: {
       token,
     },
+    // Reconnection settings
     reconnection: true,
-    reconnectionAttempts: 5,
-    reconnectionDelay: 1000,
+    reconnectionAttempts: Infinity, // Keep trying forever
+    reconnectionDelay: 1000,        // Start with 1 second delay
+    reconnectionDelayMax: 5000,     // Max 5 seconds between attempts
+    randomizationFactor: 0.5,       // Add some randomness to prevent thundering herd
+    // Timeout settings
+    timeout: 20000,                 // 20 seconds connection timeout
+    // Transport settings - prefer websocket but start with polling for reliability
+    transports: ['polling', 'websocket'],
+    upgrade: true,
   });
 
   socket.on('connect', () => {