feat: create production docker-compose.yml (#38)

- Production compose file with single app service
- Separate from development compose (now docker-compose.dev.yml)
- Environment variable configuration
- Health checks and resource limits
- .env.production.example template
- Comprehensive DEPLOYMENT.md guide

Deployment guide covers:
- Quick start with Docker Compose
- Supabase setup (cloud + self-hosted)
- Multiple deployment options (Coolify, Docker, K8s, VPS)
- HTTPS/SSL configuration
- Monitoring and logging
- Backup and restore procedures
- Troubleshooting
- Security checklist
- Performance optimization

Ready for production deployment on any platform.

Closes #38

docker-compose.prod.yml

@@ -0,0 +1,52 @@
+# Production Docker Compose for Pantry App
+# 
+# This compose file only runs the Nuxt frontend.
+# Supabase should be hosted separately (managed service or self-hosted).
+
+version: '3.8'
+
+services:
+  app:
+    build:
+      context: .
+      dockerfile: Dockerfile
+    image: pantry:latest
+    container_name: pantry-app
+    restart: unless-stopped
+    
+    ports:
+      - "3000:3000"
+    
+    environment:
+      # Supabase connection (REQUIRED - set these in .env.production)
+      NUXT_PUBLIC_SUPABASE_URL: ${NUXT_PUBLIC_SUPABASE_URL}
+      NUXT_PUBLIC_SUPABASE_ANON_KEY: ${NUXT_PUBLIC_SUPABASE_ANON_KEY}
+      
+      # Server configuration
+      NODE_ENV: production
+      HOST: 0.0.0.0
+      PORT: 3000
+    
+    healthcheck:
+      test: ["CMD", "node", "-e", "require('http').get('http://localhost:3000/api/health', (r) => {process.exit(r.statusCode === 200 ? 0 : 1)})"]
+      interval: 30s
+      timeout: 3s
+      start_period: 40s
+      retries: 3
+    
+    networks:
+      - pantry
+    
+    # Resource limits (adjust based on your needs)
+    deploy:
+      resources:
+        limits:
+          memory: 512M
+          cpus: '1.0'
+        reservations:
+          memory: 256M
+          cpus: '0.5'
+
+networks:
+  pantry:
+    driver: bridge