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

AGENTS.md

@@ -0,0 +1,18 @@
+<!-- OPENSPEC:START -->
+# OpenSpec Instructions
+
+These instructions are for AI assistants working in this project.
+
+Always open `@/openspec/AGENTS.md` when the request:
+- Mentions planning or proposals (words like proposal, spec, change, plan)
+- Introduces new capabilities, breaking changes, architecture shifts, or big performance/security work
+- Sounds ambiguous and you need the authoritative spec before coding
+
+Use `@/openspec/AGENTS.md` to learn:
+- How to create and apply change proposals
+- Spec format and conventions
+- Project structure and guidelines
+
+Keep this managed block so 'openspec update' can refresh the instructions.
+
+<!-- OPENSPEC:END -->