Add TURN configuration

Author: tyouwei

peerprep-fe/src/app/collaboration/components/AudioSharing.tsx

@@ -21,7 +21,7 @@ const AudioSharing = () => {
     process.env.NEXT_PUBLIC_AUDIO_SERVER_URL || 'http://localhost:5555';
 
   // Add TURN server credentials from environment variables
-  const TURN_SERVER = process.env.NEXT_PUBLIC_TURN_SERVER;
+  const TURN_SERVER = process.env.NEXT_PUBLIC_TURN_SERVER || '';
   const TURN_USERNAME = process.env.NEXT_PUBLIC_TURN_USERNAME;
   const TURN_CREDENTIAL = process.env.NEXT_PUBLIC_TURN_PASSWORD;
 
@@ -60,11 +60,11 @@ const AudioSharing = () => {
           { urls: 'stun:stun.l.google.com:19302' },
           { urls: 'stun:global.stun.twilio.com:3478' },
           // Add TURN server configuration
-          // {
-          //   urls: TURN_SERVER,
-          //   username: TURN_USERNAME,
-          //   credential: TURN_CREDENTIAL,
-          // },
+          {
+            urls: TURN_SERVER,
+            username: TURN_USERNAME,
+            credential: TURN_CREDENTIAL,
+          },
         ],
       },
     });