feat: 重构项目心跳数据结构并实现项目列表API

- 新增统一项目列表Redis键和迁移工具
- 实现GET /api/projects端点获取项目列表
- 实现POST /api/projects/migrate端点支持数据迁移
- 更新前端ProjectSelector组件使用真实项目数据
- 扩展projectStore状态管理
- 更新相关文档和OpenSpec规范
- 添加测试用例验证新功能

openspec/changes/update-redis-protocol/specs/redis-connection/spec.md

@@ -1,9 +1,11 @@
 ## ADDED Requirements
 
-### Requirement: Per-Project Status Key
-The system SHALL standardize a per-project Redis status key for connected projects.
+### Requirement: Per-Project Heartbeat Key
+
+The system SHALL standardize a per-project Redis heartbeat key for connected projects.
+
+#### Scenario: External project writes heartbeat
 
-#### Scenario: External project writes status
 - **WHEN** an external project integrates with this console
-- **THEN** it SHALL write a Redis STRING key named `${projectName}_项目状态`
-- **AND** the value SHALL be one of: `在线`, `离线`, `故障`, `报错`
+- **THEN** it SHALL write a Redis STRING key named `${projectName}_项目心跳`
+- **AND** the value SHALL be a JSON string containing `apiBaseUrl` and `lastActiveAt`