feat(streaming): add local TURN relay support

WebApp/.env.example

@@ -0,0 +1,5 @@
+VITE_BACKEND_URL=http://localhost:3000
+VITE_STUN_URLS=stun:stun.l.google.com:19302
+VITE_TURN_URLS=turn:localhost:3478?transport=udp,turn:localhost:3478?transport=tcp
+VITE_TURN_USERNAME=securecam
+VITE_TURN_CREDENTIAL=securecamturn

WebApp/src/lib/app/controller.js

@@ -76,8 +76,36 @@ const SOCKET_HEARTBEAT_INTERVAL_MS = 10_000;
 const MAX_STREAM_DIAGNOSTIC_SESSIONS = 12;
 const MAX_STREAM_DIAGNOSTIC_ENTRIES = 24;
 
+const parseRtcUrls = (value = '') =>
+	value
+		.split(',')
+		.map((item) => item.trim())
+		.filter(Boolean);
+
+const buildIceServers = () => {
+	const stunUrls = parseRtcUrls(import.meta.env.VITE_STUN_URLS ?? 'stun:stun.l.google.com:19302');
+	const turnUrls = parseRtcUrls(import.meta.env.VITE_TURN_URLS ?? '');
+	const turnUsername = (import.meta.env.VITE_TURN_USERNAME ?? '').trim();
+	const turnCredential = (import.meta.env.VITE_TURN_CREDENTIAL ?? '').trim();
+	const iceServers = [];
+
+	if (stunUrls.length > 0) {
+		iceServers.push({ urls: stunUrls });
+	}
+
+	if (turnUrls.length > 0) {
+		iceServers.push({
+			urls: turnUrls,
+			username: turnUsername,
+			credential: turnCredential
+		});
+	}
+
+	return iceServers.length > 0 ? iceServers : [{ urls: 'stun:stun.l.google.com:19302' }];
+};
+
 const rtcConfig = {
-	iceServers: [{ urls: 'stun:stun.l.google.com:19302' }]
+	iceServers: buildIceServers()
 };
 
 let initialized = false;