polish(web): 打磨 Web 会话界面的布局、自适应与组件一致性

1. 统一会话列宽度轴：新增 --dsh-chat-content-width（748px），输入框、todo、goal、queue、approval、plan review、ask question 等容器的宽度与边距全部由该变量推导，消除各面板之间的像素漂移，窄视口下的边缘留白也保持一致。
2. 输入框自适应与细节：控制行改为容器查询（460px 阈值以下权限选择器只显示图标+下拉，隐藏文字）；卡片圆角 20→22、行内边距调整并整体下移 2px（发送按钮除外）；permission/model 触发器统一 24px 圆角；Plan 与 Read Only 间距 +8。
3. 修复浮层菜单溢出：slash 菜单与命令弹层钳制到输入卡片宽度，超长行以省略号截断；Tooltip 增加 12px 视口边缘安全距离。
4. 增加与替换图标：Add provider 改用输入框同款加号图标（IconPlusOutline16），统一图标尺寸与字号。
5. 统一 Settings → Models 组件：补齐按钮 hover 态、select 下拉箭头不再贴边、标题区与 provider 卡片间距 +12。
6. 侧边栏交互：add workspace / group by / create session / 收起侧边栏四个图标按钮增加 500ms 延迟 tooltip（前两个向下弹出）；展开态的 New Session 不再重复显示 tooltip；侧边栏窄屏自适应收起逻辑微调。
7. 其他：hero 区 workspace 徽章右移对齐；附带 Agent Note（中英双语）记录共享宽度轴与容器查询的设计取舍。

packages/client/ui-primitives/tests/icons.spec.tsx

@@ -14,8 +14,8 @@ const icons = Object.fromEntries(
 const iconNames = Object.keys(icons)
 
 describe('ic_ds_ icon set', () => {
-  it('exports the full P-I set (45 deepsuite + 15 figma extracts + the hand-authored sparkle)', () => {
-    expect(iconNames.length).toBe(61)
+  it('exports the full P-I set (46 deepsuite + 17 figma extracts + the hand-authored sparkle)', () => {
+    expect(iconNames.length).toBe(64)
   })
 
   it.each(iconNames)('%s renders an svg with currentColor fills and no hardcoded palette', (name) => {

packages/client/ui-primitives/tests/tooltip.spec.tsx

@@ -43,8 +43,9 @@ describe('Tooltip', () => {
     const bubble = screen.getByRole('tooltip')
     expect(bubble.textContent).toBe('Open sidebar')
     expect(bubble.getAttribute('data-side')).toBe('right')
-    // jsdom rects are all-zero: right placement lands at the +10 gutter.
-    expect(bubble.style.left).toBe('10px')
+    // jsdom rects are all-zero: right placement lands at the +10 gutter, then
+    // the zero-width measured rect clamps to the 12px edge margin (10 + 12).
+    expect(bubble.style.left).toBe('22px')
     expect(bubble.style.top).toBe('0px')
     fireEvent.mouseLeave(anchor)
     expect(screen.queryByRole('tooltip')).toBeNull()
@@ -60,12 +61,69 @@ describe('Tooltip', () => {
     fireEvent.focus(anchor)
     const bubble = screen.getByRole('tooltip')
     expect(bubble.getAttribute('data-side')).toBe('bottom')
-    expect(bubble.style.left).toBe('0px')
+    // Zero-width jsdom rect at x=0 clamps to the 12px edge margin.
+    expect(bubble.style.left).toBe('12px')
     expect(bubble.style.top).toBe('8px')
     fireEvent.blur(anchor)
     expect(screen.queryByRole('tooltip')).toBeNull()
   })
 
+  // jsdom's default rects are all-zero, so the clamp tests stub the measured
+  // rect (anchor and bubble share the prototype stub) and derive expectations
+  // from it: pos.x = anchor center, then shifted by the measured overflow.
+  const rect = (left: number, right: number): DOMRect =>
+    ({ left, right, top: 0, bottom: 20, width: right - left, height: 20, x: left, y: 0, toJSON: () => ({}) })
+
+  it('clamps a bubble overflowing the right viewport edge back inside', () => {
+    const spy = vi.spyOn(Element.prototype, 'getBoundingClientRect').mockReturnValue(rect(900, 1100))
+    try {
+      render(
+        <Tooltip label="Wide" side="bottom">
+          <button type="button">anchor</button>
+        </Tooltip>,
+      )
+      fireEvent.mouseEnter(screen.getByText('anchor'))
+      // pos.x = 1000 (anchor center); measured right edge 1100 overflows the
+      // 1024 viewport's 12px safe margin (limit 1012) by 88, so the clamp
+      // shifts left to 912.
+      expect(screen.getByRole('tooltip').style.left).toBe('912px')
+    } finally {
+      spy.mockRestore()
+    }
+  })
+
+  it('clamps a bubble past the left viewport edge back inside', () => {
+    const spy = vi.spyOn(Element.prototype, 'getBoundingClientRect').mockReturnValue(rect(-20, 80))
+    try {
+      render(
+        <Tooltip label="Wide" side="bottom">
+          <button type="button">anchor</button>
+        </Tooltip>,
+      )
+      fireEvent.mouseEnter(screen.getByText('anchor'))
+      // pos.x = 30 (anchor center); measured left edge -20 underflows the
+      // 12px safe margin by 32, so the clamp shifts right to 62.
+      expect(screen.getByRole('tooltip').style.left).toBe('62px')
+    } finally {
+      spy.mockRestore()
+    }
+  })
+
+  it('supports top placement for anchors at the viewport bottom', () => {
+    render(
+      <Tooltip label="Above" side="top">
+        <button type="button">anchor</button>
+      </Tooltip>,
+    )
+    fireEvent.mouseEnter(screen.getByText('anchor'))
+    const bubble = screen.getByRole('tooltip')
+    expect(bubble.getAttribute('data-side')).toBe('top')
+    // jsdom rects are all-zero: top placement lands at the -8 gutter and the
+    // zero-width measured rect clamps left to the 12px edge margin.
+    expect(bubble.style.left).toBe('12px')
+    expect(bubble.style.top).toBe('-8px')
+  })
+
   it('chains the anchor\'s own handlers ahead of the tooltip\'s', () => {
     const onMouseEnter = vi.fn()
     const onMouseLeave = vi.fn()