feat(api): DELETE /api/projects/:id + store.deleteProject(连带 tasks/runs/events)

新增项目删除能力：store.deleteProject 事务内删 events(无 FK,手动)+ projects(tasks/runs/
approvals 经 schema ON DELETE CASCADE 连带清)；DELETE /api/projects/:id 暴露之。
store.test 覆盖连带清除 + 重复删报错。用于清理 cutover 测试遗留的一次性 smoke-test 项目
(本次经直连 DB 删除,未重启打断在跑的 worker；端点下次重启生效)。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/api/server.ts

@@ -92,6 +92,13 @@ export function buildServer(opts: ApiOptions): FastifyInstance {
     return store.reorderProjects(b.order.map(String)).map(projectOut);
   });
 
+  // 彻底删除项目（连带 tasks/runs/approvals/events，不可恢复）
+  app.delete('/api/projects/:id', (req) => {
+    const { id } = req.params as { id: string };
+    store.deleteProject(id);
+    return { ok: true };
+  });
+
   // 项目 logo：仓库内文件 → 流式返回；外链头像 → 302；无 → 404（前端用首字母徽章兜底）
   app.get('/api/projects/:id/logo', async (req, reply) => {
     const { id } = req.params as { id: string };