Initial commit: self-hosted Docker setup for OpenFrontIO

Includes docker-compose, setup script, nginx reverse proxy docs,
and GAME_ENV configuration notes for self-hosted deployments.

docker-compose.yml

@@ -0,0 +1,23 @@
+services:
+  openfront:
+    build:
+      context: ./OpenFrontIO
+      dockerfile: Dockerfile
+      args:
+        GIT_COMMIT: ${GIT_COMMIT:-unknown}
+    entrypoint: ["/usr/local/bin/startup-local.sh"]
+    ports:
+      - "${HOST_PORT:-80}:80"
+    env_file:
+      - .env
+    volumes:
+      # Override startup and supervisor config with our local versions
+      - ./startup-local.sh:/usr/local/bin/startup-local.sh:ro
+      - ./supervisord-local.conf:/etc/supervisor/conf.d/supervisord-local.conf:ro
+    restart: unless-stopped
+    healthcheck:
+      test: ["CMD", "curl", "-sf", "http://localhost/api/health"]
+      interval: 30s
+      timeout: 10s
+      retries: 3
+      start_period: 90s