feat(web+store): needs_attention 任务显示在审核区，附失败原因

- pendingApprovals 扩展到包含 needs_attention，subquery 取最近 executor 失败 error
- Task 类型增加 lastRunError 字段，mappers 映射
- 审核区（renderGates）将 needs_attention 渲染为独立橙色卡片，
  展示「需人工确认」标签 + 具体失败原因 + 重新排队/取消按钮
- i18n zh/en 补充 attnLabel/attnReason/attnRequeue/attnCancel/toastRequeued

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

src/store/mappers.ts

@@ -20,6 +20,7 @@ export interface TaskRow {
   next_eligible_at: string | null;
   created_at: string; updated_at: string;
   source_ref: string | null;
+  last_run_error?: string | null;  // pendingApprovals 扩展字段（subquery）
 }
 export interface ApprovalRow {
   id: string; task_id: string; gate: string; action: string;
@@ -75,6 +76,7 @@ export function rowToTask(r: TaskRow, approvals: ApprovalRecord[] = []): Task {
     approvals, result: r.result ? parseResult(r.result) : null,
     assignee: r.assignee as Task['assignee'], retryBaseline: r.retry_baseline ?? 0,
     nextEligibleAt: r.next_eligible_at ?? null,
+    lastRunError: r.last_run_error ?? null,
     createdAt: r.created_at, updatedAt: r.updated_at,
   };
 }