chore: add docker infrastructure, gists feature, attachment system, and admin CLI tools

- Add .dockerignore, Dockerfile, and docker compose targets to Makefile for containerized deployment
- Implement gists router with CRUD operations, database schema, and polymorphic comment/vote reuse
- Create attachment upload system with thumbnail generation, MIME detection, and storage path management
- Add attachments_prune CLI command to clean orphaned attachment records and files
- Introduce rate limiting middleware with 60 requests per minute window
- Add custom 404 and 500 error handlers with SEO-optimized template responses
- Extend database initialization with gists and attachments indexes plus upload site settings defaults
- Update load_comments to include attachment mapping for comment resources
- Register gists and uploads routers in main application and update AGENTS.md documentation

docker-compose.yml

@@ -0,0 +1,51 @@
+name: devplace
+
+services:
+  app:
+    build:
+      context: .
+      dockerfile: Dockerfile
+    restart: unless-stopped
+    env_file:
+      - .env
+    environment:
+      DEVPLACE_DATABASE_URL: sqlite:///data/devplace.db
+    volumes:
+      - devplace_data:/app/data
+      - devplace_uploads:/app/devplacepy/static/uploads
+    expose:
+      - "10500"
+    networks:
+      - appnet
+    healthcheck:
+      test: ["CMD", "curl", "-f", "http://localhost:10500/"]
+      interval: 30s
+      timeout: 10s
+      retries: 3
+      start_period: 10s
+
+  nginx:
+    build:
+      context: .
+      dockerfile: nginx/Dockerfile
+    restart: unless-stopped
+    ports:
+      - "${PORT:-80}:80"
+    environment:
+      NGINX_CACHE_ENABLED: "${NGINX_CACHE_ENABLED:-false}"
+      NGINX_CACHE_MAX_SIZE: "${NGINX_CACHE_MAX_SIZE:-1g}"
+    volumes:
+      - devplace_uploads:/app/static/uploads:ro
+    depends_on:
+      app:
+        condition: service_healthy
+    networks:
+      - appnet
+
+volumes:
+  devplace_data:
+  devplace_uploads:
+
+networks:
+  appnet:
+    driver: bridge