feat(sfu): add mediasoup runtime and router capabilities endpoint

Backend/media/sfu/service.ts

@@ -1,14 +1,20 @@
 import { mediaMode } from '../config';
+import { MediasoupSfuService } from './mediasoup';
 import { NoopSfuService } from './noop';
 import type { SfuService } from './types';
 
+const sfuEngine = (process.env.MEDIA_SFU_ENGINE ?? 'mediasoup').trim().toLowerCase();
+
 const createSfuService = (): SfuService | null => {
   if (mediaMode !== 'single_server_sfu') {
     return null;
   }
 
-  return new NoopSfuService();
+  if (sfuEngine === 'noop') {
+    return new NoopSfuService();
+  }
+
+  return new MediasoupSfuService();
 };
 
 export const sfuService = createSfuService();
-