feat: Implement the core InterNetX DDNS updater application with API, services, middleware, Docker support, and a detailed README.

docker-compose.yml

@@ -0,0 +1,50 @@
+version: '3.8'
+
+services:
+  ddns-updater:
+    build: .
+    container_name: internetx-ddns-updater
+    restart: unless-stopped
+    
+    ports:
+      - "3000:3000"
+    
+    environment:
+      - NODE_ENV=production
+      - PORT=3000
+      # InterNetX API - Configure via .env file
+      - INTERNETX_API_URL=${INTERNETX_API_URL}
+      - INTERNETX_USER=${INTERNETX_USER}
+      - INTERNETX_PASSWORD=${INTERNETX_PASSWORD}
+      - INTERNETX_CONTEXT=${INTERNETX_CONTEXT}
+      # DDNS Configuration
+      - DEFAULT_ZONE=${DEFAULT_ZONE}
+      - DEFAULT_TTL=${DEFAULT_TTL}
+      # Security
+      - AUTH_TOKENS=${AUTH_TOKENS}
+      - IP_WHITELIST=${IP_WHITELIST}
+      # Rate Limiting
+      - RATE_LIMIT_WINDOW_MS=${RATE_LIMIT_WINDOW_MS}
+      - RATE_LIMIT_MAX_REQUESTS=${RATE_LIMIT_MAX_REQUESTS}
+      # Logging
+      - LOG_LEVEL=${LOG_LEVEL}
+      - LOG_FILE_MAX_SIZE=${LOG_FILE_MAX_SIZE}
+      - LOG_FILE_MAX_AGE=${LOG_FILE_MAX_AGE}
+    
+    volumes:
+      - ./logs:/app/logs
+      - ./public:/app/public:ro
+    
+    healthcheck:
+      test: ["CMD", "node", "-e", "require('http').get('http://localhost:3000/health', (r) => {r.statusCode === 200 ? process.exit(0) : process.exit(1)})"]
+      interval: 30s
+      timeout: 3s
+      retries: 3
+      start_period: 10s
+    
+    networks:
+      - ddns-network
+
+networks:
+  ddns-network:
+    driver: bridge