Enhance socketService configuration for WebSocket upgrades

This commit updates the `socketService.js` file to improve WebSocket upgrade handling by adding two new configuration options: `allowEIO3`, which permits WebSocket upgrades without an Origin header, and `serveClient`, which disables serving the client bundle. These changes enhance compatibility with reverse proxies and optimize the WebSocket connection process.

backend/services/socketService.js

@@ -18,7 +18,11 @@ export const initializeSocketIO = (httpServer) => {
     upgradeTimeout: 10000,
     // Ping-Timeout für Verbindungen
     pingTimeout: 60000,
-    pingInterval: 25000
+    pingInterval: 25000,
+    // Wichtig für Reverse Proxy: Erlaube WebSocket-Upgrades auch ohne Origin-Header
+    allowEIO3: true,
+    // Erlaube WebSocket-Upgrades auch wenn der Request von einem Proxy kommt
+    serveClient: false
   });
 
   io.on('connection', (socket) => {