Add Docker-based production deployment

- Multi-stage Dockerfile with Node builder and nginx server
- Nginx configuration with gzip, security headers, and caching
- Docker Compose setup with health checks
- Updated README with deployment instructions

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

docker-compose.yml

@@ -0,0 +1,24 @@
+version: '3.8'
+
+services:
+  whalehunting-game:
+    build:
+      context: .
+      dockerfile: Dockerfile
+    image: whalehunting-game:latest
+    container_name: whalehunting-game
+    ports:
+      - "8080:80"
+    restart: unless-stopped
+    healthcheck:
+      test: ["CMD", "wget", "--quiet", "--tries=1", "--spider", "http://localhost/"]
+      interval: 30s
+      timeout: 3s
+      retries: 3
+      start_period: 5s
+    networks:
+      - whalehunting-network
+
+networks:
+  whalehunting-network:
+    driver: bridge