fix(deploy): use expose instead of host ports for Coolify compose

Coolify honors host port bindings in the compose and the host already has :80
(its own proxy) and :8000 allocated, so publishing them fails the deploy at
container start. Switch web/api to expose-only; nginx still reaches api over the
compose network, and Coolify routes the domain via docker_compose_domains. Add a
docker-compose.override.yml so local 'docker compose up' still publishes ports.

README.md

@@ -23,7 +23,7 @@ service (see `nginx.conf` + `docker-compose.yml`).
 pnpm install
 pnpm dev                                  # frontend on :5173 (proxies /api -> :8000)
 cd backend && pnpm install && pnpm dev    # API on :8000
-# …or run the whole stack in containers:
+# …or run the whole stack in containers (open http://localhost:8080):
 docker compose up --build
 ```