feat: 实现RCU固件升级服务核心功能

- 添加升级服务主逻辑，包括定时触发升级、状态查询和日志记录
- 实现数据库初始化脚本和日志表结构
- 添加PM2部署配置文件
- 实现环境变量配置系统
- 添加API客户端模块处理外部接口调用
- 实现升级状态轮询和超时处理机制
- 添加测试用例验证核心功能

scripts/init_db.sql

@@ -0,0 +1,25 @@
+-- Create database (run manually or via script if user has permissions)
+-- CREATE DATABASE test_upgrade;
+
+-- Connect to test_upgrade before running the following:
+
+CREATE TABLE IF NOT EXISTS upgrade_log (
+    uuid UUID NOT NULL,
+    start_time TIMESTAMP NOT NULL,
+    roomtype_id INTEGER NOT NULL,
+    host_str TEXT NOT NULL,
+    filename TEXT NOT NULL,
+    status TEXT,
+    end_time TIMESTAMP,
+    file_type TEXT,
+    config_version TEXT,
+    firmware_version TEXT,
+    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
+);
+
+CREATE TABLE IF NOT EXISTS upgrade_state (
+    state_key TEXT PRIMARY KEY,
+    current_roomtype_index INTEGER DEFAULT 0,
+    execution_count INTEGER DEFAULT 0,
+    last_updated TIMESTAMP DEFAULT CURRENT_TIMESTAMP
+);