feat: DM infrastructure overhaul + volume sliders + LiveKit dynamic URL

- Add DM edit/delete endpoints (REST + WebSocket)
- Add DM typing indicators with real-time broadcast
- Fix volume sliders to control LiveKit mic/speaker
- Fix Send Message button on user profile popout
- Add New DM modal with user search
- Fix message pagination (SQL cursor instead of in-memory)
- Guard optional attachments on DM messages
- Dynamic LiveKit URL from request Host header
- DM sidebar auto-sorts by most recent message

packages/server/src/routes/livekit.ts

@@ -41,9 +41,16 @@ export async function livekitRoutes(app: FastifyInstance): Promise<void> {
 
     const jwt = await token.toJwt();
 
-    const response: LiveKitTokenResponse = { 
+    // Use the request's Host header so the LiveKit WSS URL matches however
+    // the client reached us (domain or direct IP).
+    const requestHost = request.headers.host?.replace(/:\d+$/, '') || '';
+    const livekitUrl = requestHost
+      ? `wss://${requestHost}/livekit`
+      : config.livekit.url;
+
+    const response: LiveKitTokenResponse = {
       token: jwt,
-      url: config.livekit.url
+      url: livekitUrl
     };
     return reply.code(200).send(response);
   });