feat(icons): file icons and tab glyphs in color, from the host's own artwork

Issue #611 asked for file-type icons like the official explorer's, and #429
built a colored theme for them. DSH 0.1.5-rc.2 makes most of that work
unnecessary: `@deepseek-ai/dsh-client-ui-primitives` now exports
`FileTypeIcon` / `CodeFileIcon` with the host's own 48-type full-color code
artwork plus category-colored sheet glyphs (and its classifier behind them).
So the plugin renders the host's icons instead of shipping a color table, and
color becomes the only behaviour rather than an opt-in theme.

File icons (src/client/file-icons.tsx)
- `builtinFileIcon(path, size)` → `<FileTypeIcon path size />`; folders use the
  host's folder category. The plugin's own per-extension VSCodicon map is gone.
- The public `registerFileIcon` API from #531 is unchanged and still outranks
  the built-ins, so an external plugin can take over any row. One semantic
  consequence, now documented and tested: because the host classifier covers
  every path, a registered catch-all (`exts: []`) claims rows it used to lose
  to the built-in map. An unregistered catch-all (the old icon theme's shape)
  is unaffected.
- Nothing is lazy any more: the artwork lives in a platform module the client
  already holds, so `lib/client-file-icons.js` and its 563-entry dataset (255
  kB) are deleted outright — the core bundle grew by 10 kB (0.85 → 0.86 MB).
- `src/client/file-icon-theme.ts`, the `fileIconTheme` pref (prefs-shared /
  config / client prefs), the settings-page select row and the six
  `settingsFileIconTheme*` keys in all 20 dictionaries are removed with it.

Tab glyphs (src/client/builtins/tab-icons.tsx)
- Every built-in tab type now declares a colored glyph: files (the host's
  folder artwork), changes/diff (commit), tasks (checklist), side chat
  (discussion), terminal (shell), browser (globe).
- The color comes from a `--dsw-alias-*` token through a wrapper class, never
  from a literal — the skin contract (§12) holds and `tests/theme.spec.ts`
  enforces both halves (no literals in the module, every color declaration in
  the stylesheet resolves to a token).

Native right Sidebar chips (src/client/native/tab-adapter.tsx)
- The host's tab definition has no icon field, but the
  `sidebar.right.pane.tab.title` slot IS the chip's content, so the plugin
  draws the glyph itself: an editor tab with a path shows that file's icon,
  every other tab shows its descriptor's icon — the same `descriptor.icon` the
  workbench strip and the guide capsules already render, so the three cannot
  drift. The glyph is `aria-hidden`, which keeps the chip's accessible name
  exactly the title the mount lane matches on.

Gates: typecheck / lint / check:consumer-types green; pnpm test 127 files /
1342 passed / 9 skipped (3 new chip cases, 1 rewritten built-in case).

tests/native-surface.spec.ts

@@ -8,7 +8,7 @@ import { describe, expect, it, vi } from 'vitest'
 import { createElement } from 'react'
 import { createRoot, type Root } from 'react-dom/client'
 import { act } from 'react-dom/test-utils'
-import { createNativeTabRecords, NativeTabBody } from '../src/client/native/tab-adapter.tsx'
+import { createNativeTabRecords, NativeTabBody, NativeTabTitle } from '../src/client/native/tab-adapter.tsx'
 import { registerNativeSurface } from '../src/client/native/index.ts'
 import { createBetterSidebarService, type SidebarSurface } from '../src/client/service.ts'
 import { createSidebarStore } from '../src/client/state.ts'
@@ -310,3 +310,111 @@ describe('NativeTabBody full-height host wrapper', () => {
     host.remove()
   })
 })
+
+/**
+ * The native tab CHIP: the host's tab definition carries no icon field, so
+ * the plugin draws the glyph itself inside the `sidebar.right.pane.tab.title`
+ * slot (which IS the chip's content). These cases pin the placement rule —
+ * an editor tab with a path shows the FILE's glyph, every other tab shows its
+ * descriptor's glyph — and the accessible-name boundary: the glyph is
+ * decorative, so the chip's name stays exactly the title the e2e lane matches
+ * with `getByRole('tab', { name })`.
+ */
+describe('NativeTabTitle (the chip glyph)', () => {
+  const renderTitle = (
+    records: ReturnType<typeof createNativeTabRecords>,
+    service: ReturnType<typeof createBetterSidebarService>,
+    info: unknown,
+    descriptorId: string,
+  ): { host: HTMLDivElement; unmount: () => void } => {
+    const host = document.createElement('div')
+    document.body.appendChild(host)
+    let root: Root | undefined
+    act(() => {
+      root = createRoot(host)
+      root.render(createElement(NativeTabTitle, {
+        records,
+        service,
+        descriptorId,
+        useTabInfo: () => info as never,
+      }))
+    })
+    return {
+      host,
+      unmount: () => {
+        act(() => { root?.unmount() })
+        host.remove()
+      },
+    }
+  }
+
+  const nativeInfo = (id: string, kind: string, title: string) => ({
+    tab: {
+      id,
+      kind,
+      title,
+      contentId: `sidebar://${id}`,
+      visible: true,
+      navigation: { address: `sidebar://${id}`, params: undefined, revision: 0 },
+      signal: new AbortController().signal,
+    },
+  })
+
+  it('draws the descriptor glyph before the live title', () => {
+    const records = createNativeTabRecords()
+    const service = createBetterSidebarService(createSidebarStore())
+    service.registerTab({
+      id: 'stub-tab',
+      title: () => 'Stub',
+      icon: (size: number) => createElement('i', { 'data-stub-icon': size }),
+      component: () => createElement('div'),
+    })
+    records.ensure({ id: 'chip-1', kind: 'stub-tab', title: 'Stub', params: undefined, scope })
+
+    const { host, unmount } = renderTitle(records, service, nativeInfo('chip-1', 'stub-tab', 'Stub'), 'stub-tab')
+    const chip = host.querySelector('[aria-hidden="true"]')
+    expect(chip, 'the chip must carry a decorative glyph').not.toBeNull()
+    expect(chip!.querySelector('[data-stub-icon="14"]'), 'the descriptor icon renders at the chip scale').not.toBeNull()
+    expect(host.textContent, 'the title follows the glyph').toBe('Stub')
+    expect(host.querySelector('[role="tab"]'), 'the chip itself is the host’s element, not the plugin’s').toBeNull()
+    unmount()
+  })
+
+  it('an editor tab with a path shows the FILE glyph instead of the type glyph', () => {
+    const records = createNativeTabRecords()
+    const service = createBetterSidebarService(createSidebarStore())
+    service.registerTab({
+      id: 'editor',
+      title: () => 'Files',
+      icon: (size: number) => createElement('i', { 'data-type-icon': size }),
+      component: () => createElement('div'),
+    })
+    records.ensure({
+      id: 'chip-2',
+      kind: 'editor',
+      title: 'notes.md',
+      params: { path: '/work/notes.md' },
+      scope,
+    })
+
+    const { host, unmount } = renderTitle(records, service, nativeInfo('chip-2', 'editor', 'notes.md'), 'editor')
+    expect(host.querySelector('[data-type-icon]'), 'the type glyph must NOT be used for a file tab').toBeNull()
+    // The file glyph is the host's own FileTypeIcon (its component identity is
+    // asserted through the resolver tests); here the point is that a glyph is
+    // drawn and the title is intact.
+    expect(host.querySelector('[aria-hidden="true"]')).not.toBeNull()
+    expect(host.textContent).toBe('notes.md')
+    unmount()
+  })
+
+  it('falls back to the title alone when the type is gone (unregistered descriptor)', () => {
+    const records = createNativeTabRecords()
+    const service = createBetterSidebarService(createSidebarStore())
+    records.ensure({ id: 'chip-3', kind: 'ghost', title: 'Ghost', params: undefined, scope })
+
+    const { host, unmount } = renderTitle(records, service, nativeInfo('chip-3', 'ghost', 'Ghost'), 'ghost')
+    expect(host.querySelector('[aria-hidden="true"]')).toBeNull()
+    expect(host.textContent).toBe('Ghost')
+    unmount()
+  })
+})