fix(tasks): 扫光改为整条完整扫过 + 折叠/展开按钮分向

用户反馈两条：

1) 扫光只有「部分」：第一版是 45% 宽的窄带 + background-position 位移，
   亮带始终只覆盖小条的一部分（峰值 22.5%→77.5%，两端扫不到），看起来像
   中间游走的一块光斑。改为与小条等宽的渐变带 + transform
   translateX(-100%) → translateX(100%)：光带从左外侧进入、中途覆盖整条、
   再向右外侧离开，行程用条宽本身表达（任意条宽成立），末 1/3 周期停在
   右侧外侧留白。theme.spec 新增守护钉住该形状（宽度 100%、transform 行程、
   不再有 background-position/size 位移）。

2) 折叠按钮与展开按钮长得一样：三处控件原本共用向下箭头（控制条的折叠开关
   更是无论折叠还是展开都画同一个清单图标）。现按动作方向区分——
   卡片小条的逐节点按钮 = chevron up（收进聚合），聚合卡片 = chevron down
   （展开），控制条开关随状态在两者之间切换（并复用同一个折叠图标）。
   组件守护见 tasks-page.spec 的「draws COLLAPSE and EXPAND with different
   glyphs」。

真机证据（3080，真实运行中的后台任务）：242px 小条上每 90ms 采样 ::after 的
matrix 平移量得到 [-23,32,85,131,163,-139,-94,-46,9,64,114,152,179,188]
（左侧 -139 → 右侧 +188，跨度超过一个条宽，单调推进）；三处 svg 比对
expandVsCollapse / clusterMatchesExpand / clusterFlips / clusterCollapseMatchesCard
全部为 true。

验证：typecheck / lint ✅；pnpm test 1256 passed / 9 skipped（新增 2 例）。

(cherry picked from commit 0bb8228e6a7acb4302d9a8a9881d2df04a285152)

tests/tasks-page.spec.tsx

@@ -718,6 +718,35 @@ describe('Tasks page: the shared task window', () => {
     unmount()
   })
 
+  it('draws COLLAPSE and EXPAND with different glyphs (cluster, card, aggregate)', async () => {
+    const store = makeStore(snapshotWithChildren(2))
+    const { container, unmount } = renderRoot(
+      createElement(SubagentView, { sessionId: 'root', active: true, ctx: makeCtx(store) }),
+    )
+    await flushJobs()
+    /** The icon markup of one control (the glyph is what the reader compares). */
+    const glyph = (selector: string): string =>
+      container.querySelector(selector)?.querySelector('svg')?.innerHTML ?? ''
+
+    // Folded by default: the cluster's switch offers EXPAND, and it wears the
+    // same expand glyph the aggregate card's bar does.
+    const expandGlyph = glyph('button[aria-label="展开已完成的节点"]')
+    expect(expandGlyph).not.toBe('')
+    expect(glyph('[data-graph-node^="fold:"] [data-card-bar]')).toBe(expandGlyph)
+
+    // Unfold: the cards' own control COLLAPSES one node, and it must not share
+    // the expand glyph (the reader's report was that both looked identical).
+    await act(async () => {
+      (container.querySelector('button[aria-label="展开已完成的节点"]') as HTMLButtonElement).click()
+    })
+    const collapseGlyph = glyph('[data-graph-node] button[aria-label="收进已完成聚合"]')
+    expect(collapseGlyph).not.toBe('')
+    expect(collapseGlyph).not.toBe(expandGlyph)
+    // The cluster switch flips to the collapse direction with the same glyph.
+    expect(glyph('button[aria-label="折叠已完成的节点"]')).toBe(collapseGlyph)
+    unmount()
+  })
+
   it('offers no fold chevron on a running card or on the current session', async () => {
     livePayload = { 'child-0': { running: true, summary: { counts: [], runningDetail: '' } } }
     const store = makeStore(snapshotWithChildren(2))

tests/theme.spec.ts

@@ -161,6 +161,26 @@ describe('skin contract: the plugin owns no color of its own', () => {
     }
   })
 
+  it('the running bar sweeps the FULL width (a band either side, not a partial blob)', () => {
+    // Reader report: the first cut moved a 45%-wide band with
+    // `background-position`, so the bar was only ever partially lit. The
+    // corrected rule is a bar-wide band whose TRANSFORM travels one full width
+    // either side of the bar — entered at the left edge, covering the bar
+    // mid-flight, gone past the right edge.
+    const styles = readFileSync(resolve(ROOT, 'src/client/tasks-graph.module.css'), 'utf8')
+    const block = /\.cardBar\[data-running='true'\]::after \{([\s\S]*?)\n\}/.exec(styles)?.[1]
+    if (block === undefined) throw new Error('the running bar sweep rule must exist')
+    expect(block).toContain('width: 100%')
+    expect(block).toContain('transform: translateX(-100%)')
+    // No residual background-position travel (the partial-sweep mechanism).
+    expect(block).not.toContain('background-position')
+    expect(block).not.toContain('background-size')
+    const frames = /@keyframes dsh-tasks-bar-sweep \{([\s\S]*?)\n\}/.exec(styles)?.[1]
+    if (frames === undefined) throw new Error('the sweep keyframes must exist')
+    expect(frames).toContain('transform: translateX(-100%)')
+    expect(frames).toContain('transform: translateX(100%)')
+  })
+
   it('the empty-pane welcome capsule follows the host guide recipe', () => {
     // The card is the same surface as DSH's own guide capsule ("pick what
     // opens here"), so this pins the shared geometry and the token-only