Add compose override for VPSes that already run Nginx

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docker-compose.nginx.yml

@@ -0,0 +1,17 @@
+# Use this when the VPS already runs Nginx (it owns ports 80/443 and the TLS certificate).
+# Runs only Postgres + the app, published on localhost for Nginx to proxy to:
+#   docker compose -f docker-compose.yml -f docker-compose.nginx.yml up -d --build db app
+# Nginx site for the app domain:
+#   location / {
+#     proxy_pass http://127.0.0.1:3310;
+#     proxy_http_version 1.1;
+#     proxy_set_header Host $host;
+#     proxy_set_header X-Forwarded-Proto $scheme;
+#     proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+#     proxy_set_header X-Real-IP $remote_addr;
+#     client_max_body_size 20m;
+#   }
+services:
+  app:
+    ports:
+      - "127.0.0.1:3310:3000"