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

src/frontend/views/SidebarView.vue

@@ -10,7 +10,10 @@
 <script setup>
 import { computed } from 'vue';
 import ProjectSelector from '../components/ProjectSelector.vue';
-import { selectedProjectId, setSelectedProject } from '../store/projectStore.js';
+import {
+  selectedProjectId,
+  setSelectedProject,
+} from '../store/projectStore.js';
 
 const selectedId = computed(() => selectedProjectId.value);
 
@@ -27,4 +30,4 @@ const handleProjectSelected = (project) => {
   height: 100%;
   overflow-y: auto;
 }
-</style>
+</style>