chore(deploy): Docker production config, nginx gzip/cache, deploy docs

- docker-compose.yml: restart always, env_file, named volume, start_period
- frontend/nginx.conf: gzip compression, cache headers for assets, no-cache for SW
- Makefile: add prod-down and prod-logs targets
- docs/DEPLOY.md: Dokploy + Cloudflare Tunnel deploy instructions

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docker-compose.yml

@@ -1,25 +1,33 @@
 services:
   backend:
     build: ./backend
-    restart: unless-stopped
+    restart: always
+    env_file: .env
     volumes:
-      - ./backend/data:/app/data
+      - backend-data:/app/data
     environment:
       - DATABASE_URL=sqlite+aiosqlite:///./data/roaauto.db
-      - SECRET_KEY=${SECRET_KEY}
-      - SMSAPI_TOKEN=${SMSAPI_TOKEN:-}
       - CORS_ORIGINS=https://roaauto.romfast.ro
     healthcheck:
       test: ["CMD-SHELL", "curl -f http://localhost:8000/api/health || exit 1"]
       interval: 30s
       timeout: 10s
       retries: 3
+      start_period: 15s
 
   frontend:
     build: ./frontend
-    restart: unless-stopped
+    restart: always
     ports:
       - "80:80"
     depends_on:
       backend:
         condition: service_healthy
+
+volumes:
+  backend-data:
+    driver: local
+    driver_opts:
+      type: none
+      o: bind
+      device: ./backend/data