feat(tasks): 空闲成员 ≥3 时自动收进聚合，聚合并如实报出状态配比

用户要求优化显示：「比如空闲时也折叠」。

在此之前，一个跑完一轮的 teammate（活体通道不报 running）映射成 idle，
而 idle 不在「已完成/出错」的可折叠集合里 —— 于是 8 人团队永远摆 8 张卡，
而同样「不在执行」的普通子代理却是 done、会折叠。同一事实两种显示，才是
这个痛点的根。

- 可折叠集合放宽到「不在执行」（done | idle | error）；运行中/部署中永不折叠。
- 空闲**不无条件收**：按用户确认的阈值，一个父节点下空闲成员 ≥3 才随页面级
  折叠规则一起收（FOLD_IDLE_MIN）。1–2 个待命成员就是这个团队的工作集，
  而且它们的卡上会挂任务行，留着看；3 个以上才是「在扫名册」。
- 聚合行如实报账：聚合节点新增 doneCount/idleCount/errorCount/hasIdle，
  小条写 `✓ N 已完成 · N 待命 · 出错 N`（为零的项省略，全已完成时与原先一样短），
  徽标在**没有已完成项**时改说 `N 待命` —— 否则「✓ N 已完成」会把待命和出错
  一起算成已完成，是撒谎。图卡片与树行共用 foldTally/foldBadgeCount。
- 手动折叠（卡片 chevron）不设阈值：那是读者点名要收的节点。
- i18n：新增 tasksFoldIdle ×20 词典。

测试：新增 6 例（阈值命中收 3 个空闲成员、2 个保持可见、运行中成员即使达标也不收、
混合聚合按状态计数、页面聚合行报「3 待命」且徽标不说已完成）；pnpm test
1284 passed / 9 skipped，typecheck / lint 通过。

(cherry picked from commit 39d66ffb2e93eeb4095ec1cb2ac15933cce62742)

tests/tasks-model.spec.ts

@@ -226,6 +226,78 @@ describe('buildTasksModel', () => {
     expect(fold).toMatchObject({ parentId: 'root', count: 2, memberIds: ['done-1', 'done-2'] })
   })
 
+  it('sweeps idle team members once a parent has FOLD_IDLE_MIN of them', () => {
+    // Three idle teammates = a roster the reader scans, not a working set:
+    // they fold, and the aggregate keeps saying who is only waiting.
+    const mates = ['m1', 'm2', 'm3']
+    const model = buildTasksModel(input({
+      catalogs: {
+        root: catalog(mates.map(id => child(id))),
+        ...Object.fromEntries(mates.map(id => [id, catalog([])])),
+      },
+      byId: Object.fromEntries([['root', summary('root')], ...mates.map(id => [id, summary(id)])]),
+      teamMembers: mates.map(id => member({ id, name: id, status: 'idle' })),
+    }))
+    expect(model.map(node => node.id)).toEqual(['root', 'fold:root'])
+    expect(model.find(node => node.kind === 'fold')).toMatchObject({
+      count: 3, doneCount: 0, idleCount: 3, errorCount: 0, hasIdle: true,
+      memberIds: ['m1', 'm2', 'm3'],
+    })
+  })
+
+  it('keeps two idle team members visible (below the threshold)', () => {
+    const mates = ['m1', 'm2']
+    const model = buildTasksModel(input({
+      catalogs: {
+        root: catalog(mates.map(id => child(id))),
+        ...Object.fromEntries(mates.map(id => [id, catalog([])])),
+      },
+      byId: Object.fromEntries([['root', summary('root')], ...mates.map(id => [id, summary(id)])]),
+      teamMembers: mates.map(id => member({ id, name: id, status: 'idle' })),
+    }))
+    expect(model.map(node => node.id)).toEqual(['root', 'm1', 'm2'])
+  })
+
+  it('never sweeps a RUNNING member even when the idle head count is met', () => {
+    const model = buildTasksModel(input({
+      catalogs: {
+        root: catalog(['m1', 'm2', 'm3', 'busy'].map(id => child(id))),
+        ...Object.fromEntries(['m1', 'm2', 'm3', 'busy'].map(id => [id, catalog([])])),
+      },
+      byId: Object.fromEntries(
+        [['root', summary('root')], ...['m1', 'm2', 'm3', 'busy'].map(id => [id, summary(id)])],
+      ),
+      live: running('busy'),
+      teamMembers: [
+        ...['m1', 'm2', 'm3'].map(id => member({ id, name: id, status: 'idle' })),
+        member({ id: 'busy', name: 'busy', status: 'running' }),
+      ],
+    }))
+    expect(model.map(node => node.id)).toEqual(['root', 'busy', 'fold:root'])
+    expect(model.find(node => node.kind === 'fold')).toMatchObject({ idleCount: 3, doneCount: 0 })
+  })
+
+  it('counts a mixed aggregate per state so the tally cannot over-claim', () => {
+    const model = buildTasksModel(input({
+      catalogs: {
+        root: catalog([child('m1'), child('m2'), child('m3'), child('done-1'), child('failed-1')]),
+        ...Object.fromEntries(
+          ['m1', 'm2', 'm3', 'done-1', 'failed-1'].map(id => [id, catalog([])]),
+        ),
+      },
+      byId: Object.fromEntries(
+        [['root', summary('root')], ...['m1', 'm2', 'm3', 'done-1', 'failed-1'].map(id => [id, summary(id)])],
+      ),
+      teamMembers: [
+        ...['m1', 'm2', 'm3'].map(id => member({ id, name: id, status: 'idle' })),
+        member({ id: 'failed-1', name: 'failed-1', phase: 'failed', status: 'failed' }),
+      ],
+    }))
+    expect(model.find(node => node.kind === 'fold')).toMatchObject({
+      count: 5, doneCount: 1, idleCount: 3, errorCount: 1,
+    })
+  })
+
   it('keeps a child whose own catalog is unknown (never folds on missing data)', () => {
     const model = buildTasksModel(input({
       catalogs: { root: catalog([child('opaque')]) },

tests/tasks-page.spec.tsx

@@ -827,6 +827,26 @@ describe('Tasks page: the shared task window', () => {
     unmount()
   })
 
+  it('reports the idle part of the aggregate instead of claiming everything is done', async () => {
+    // Three idle teammates meet the idle head count, so the team folds — and
+    // the aggregate row has to say that they are WAITING, not finished.
+    const mate = (index: number): SidebarTeamMemberProjection => ({
+      id: `child-${index}`, name: `mate-${index}`, role: 'teammate', phase: 'active',
+    })
+    withTeam({ members: [{ id: 'root', name: 'lead', role: 'lead', phase: 'active' }, ...[0, 1, 2].map(mate)] })
+    const store = makeStore(snapshotWithChildren(3))
+    const { container, unmount } = renderRoot(
+      createElement(SubagentView, { sessionId: 'root', active: true, ctx: makeCtx(store) }),
+    )
+    await flushJobs()
+    const aggregate = container.querySelector('[data-graph-node="fold:root"]') as HTMLElement
+    expect(aggregate).not.toBeNull()
+    expect(aggregate.textContent).toContain('3 待命')
+    // Nothing was completed, so the badge must not claim a completed count.
+    expect(aggregate.textContent).not.toContain('已完成')
+    unmount()
+  })
+
   it('draws COLLAPSE and EXPAND with different glyphs (cluster, card, aggregate)', async () => {
     const store = makeStore(snapshotWithChildren(2))
     const { container, unmount } = renderRoot(