Deploy from a Gitea registry image instead of building on the server

CI now builds and pushes the image to the Gitea container registry, links
the package, and the deploy job ships only deploy/docker-compose.yml and an
.env naming the image to /opt/vending-machine-game.

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

deploy/docker-compose.yml

@@ -0,0 +1,17 @@
+# Server deployment: runs the prebuilt image from the Gitea registry behind Nginx Proxy Manager.
+# NPM terminates HTTPS and forwards to http://vending-machine-game:80 on the frontend_proxy network.
+# IMAGE is set in .env next to this file (CI writes it on every deploy).
+services:
+  game:
+    image: ${IMAGE:?set IMAGE in .env}
+    container_name: vending-machine-game
+    restart: unless-stopped
+    environment:
+      # Plain HTTP inside the network; no host ports are published.
+      SITE_ADDRESS: ":80"
+    networks:
+      - frontend_proxy
+
+networks:
+  frontend_proxy:
+    external: true