feat: 重试与超时策略细化（可配 + 退避）tsk_N5wO3Armums2

## 变更摘要

### 1. 项目级可配重试上限与超时
- `Project` 新增 `maxRetries`（默认 2）和 `timeoutMs`（默认 30min = 1800000ms）字段
- SQLite schema：`projects` 表补 `max_retries` / `timeout_ms` 列（带 DEFAULT 的轻量迁移）
- `createProject` / `patchProject` 支持设置 / 校验新字段（maxRetries>=0, timeoutMs>=1000）
- API `POST /api/projects` 与 `PATCH /api/projects/:id` 透传新字段
- `runner.ts` 将 `project.timeoutMs` 传给 `runClaude`，不再固定 30min

### 2. 失败重试指数退避
- 编排器内存维护 `backoffUntil` Map（taskId → nextRetryAt），daemon 重启后清空
- 退避公式：`min(30s * 2^(attempt-1), 10min)`，第 1 次 30s / 第 2 次 60s / ...
- `claimable()` 过滤退避冷却中的任务
- `nowMs` 注入点（默认 `Date.now`）使测试可快进时钟验证退避行为

### 3. needs_attention 一键重投
- `Task` 新增 `retryBaseline` 字段（默认 0）：记录上次重投时的失败 run 基线
- `Store.requeueTask(taskId)`：设置基线 = 当前失败 run 数 → 转 `queued`（仅限 needs_attention）
- 编排器用净失败数（`allFailed - retryBaseline`）判断是否已耗尽重试次数
- API `POST /api/tasks/:id/requeue` + MCP `requeue_task` 工具

### 4. 测试
- 重命名 `MAX_RETRIES` → `DEFAULT_MAX_RETRIES`，新增导出 `computeBackoffMs`
- 新增测试（共 +18）：maxRetries=1/0、退避时序（精确 ms 边界）、重投后基线重置
- 迁移测试扩展：验证旧库补列后 maxRetries/timeoutMs/retryBaseline 使用默认值

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/api/server.ts

@@ -52,6 +52,8 @@ export function buildServer(opts: ApiOptions): FastifyInstance {
       verifyCmd: b.verifyCmd === undefined ? undefined : (b.verifyCmd === null ? null : String(b.verifyCmd)),
       autonomy: b.autonomy as never, model: b.model === undefined ? undefined : (b.model === null ? null : String(b.model)),
       concurrency: b.concurrency === undefined ? undefined : Number(b.concurrency),
+      maxRetries: b.maxRetries === undefined ? undefined : Number(b.maxRetries),
+      timeoutMs: b.timeoutMs === undefined ? undefined : Number(b.timeoutMs),
     }));
   });
 
@@ -73,6 +75,8 @@ export function buildServer(opts: ApiOptions): FastifyInstance {
     if (b.verifyCmd !== undefined) patch.verifyCmd = b.verifyCmd === null ? null : String(b.verifyCmd);
     if (b.model !== undefined) patch.model = b.model === null ? null : String(b.model);
     if (b.logo !== undefined) patch.logo = b.logo === null || b.logo === '' ? null : String(b.logo);
+    if (b.maxRetries !== undefined) patch.maxRetries = Number(b.maxRetries);
+    if (b.timeoutMs !== undefined) patch.timeoutMs = Number(b.timeoutMs);
     return projectOut(store.patchProject(id, patch));
   });
 
@@ -226,6 +230,12 @@ export function buildServer(opts: ApiOptions): FastifyInstance {
     return store.transition(id, b.to as TaskStatus, b.meta ?? {});
   });
 
+  // needs_attention 任务一键重投：重置重试基线 + 转 queued，让编排器下一轮重新领取
+  app.post('/api/tasks/:id/requeue', (req) => {
+    const { id } = req.params as { id: string };
+    return store.requeueTask(id);
+  });
+
   // 审批闸：accept / reject（reject 必带 reason）
   // exec 闸的 accept = 通过并合并（PR 闭环）：先 merge 再 decide；merge 失败 → 400，任务保留在审核闸。
   app.post('/api/tasks/:id/decide', async (req) => {