🧑‍💻(docker) split frontend to another file

This commit aims at improving the user experience:
- Use a dedicated `Dockerfile` for the frontend
- Run the backend and frontend in "watch"/dev mode in Docker
- Do not start all Docker instances for small tasks

src/frontend/apps/desk/conf/default.conf

@@ -1,4 +1,5 @@
 server {
+  listen 3000;
   listen 8080;
   server_name localhost;
   server_tokens off;