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/theme.spec.ts

@@ -85,36 +85,48 @@ describe('effectiveTokenValue', () => {
 
 /**
  * Skin contract (guide §12): every visual value rides a `--dsw-alias-*` /
- * `--dsw-font-*` / `--ds-*` token. The ONE documented exception is the
- * optional colored icon theme: brand colors are identity, not chrome, so
- * they are hardcoded — but only inside the lazy `file-icons` chunk, which
- * the core bundle must never import. This guards that boundary.
+ * `--dsw-font-*` / `--ds-*` token, and the plugin draws no color of its own.
+ *
+ * File icons are no exception to check any more: the built-in set IS DSH's
+ * `FileTypeIcon` artwork from a platform module (the host owns those pixels
+ * and its own palette), and everything the plugin renders around them —
+ * including the colored tab glyphs — rides theme tokens. So the guard is
+ * simply that no plugin module carries a color literal, and that no icon
+ * dataset sneaked back in as a chunk.
  */
 // jsdom has no file:// import.meta.url; vitest runs from the repo root.
 const ROOT = process.cwd()
 
-describe('skin contract boundary for hardcoded icon colors', () => {
-  const coreIconModules = ['src/client/file-icons.tsx', 'src/client/file-icon-theme.ts']
-
-  it('the core icon modules carry no color literals', () => {
-    for (const file of coreIconModules) {
+describe('skin contract: the plugin owns no color of its own', () => {
+  it('the icon modules carry no color literals', () => {
+    for (const file of ['src/client/file-icons.tsx', 'src/client/icons.tsx']) {
       const source = readFileSync(resolve(ROOT, file), 'utf8')
       expect(source, file).not.toMatch(/#[0-9a-fA-F]{3,8}\b/)
       expect(source, file).not.toMatch(/\brgba?\(/)
     }
   })
 
-  it('only the lazy chunk may carry the colored dataset, and the core never imports it statically', () => {
-    const chunk = readFileSync(resolve(ROOT, 'src/client/chunks/file-icons.tsx'), 'utf8')
-    expect(chunk).toMatch(/#[0-9a-fA-F]{6}/)
-    const clientDir = resolve(ROOT, 'src/client')
-    const offenders: string[] = []
-    for (const entry of readdirSync(clientDir, { recursive: true, withFileTypes: true })) {
-      if (!entry.isFile() || !/\.tsx?$/.test(entry.name)) continue
-      const path = resolve(entry.parentPath, entry.name)
-      if (path.includes('/chunks/')) continue
-      if (/from '[^']*chunks\/file-icons/.test(readFileSync(path, 'utf8'))) offenders.push(path)
+  it('the colored tab glyphs take their color from theme tokens, never from a literal', () => {
+    const module = readFileSync(resolve(ROOT, 'src/client/builtins/tab-icons.tsx'), 'utf8')
+    expect(module).not.toMatch(/#[0-9a-fA-F]{3,8}\b/)
+    expect(module).not.toMatch(/\brgba?\(/)
+    // Each glyph is wrapped in a themed class, which is how the color arrives.
+    const styles = readFileSync(resolve(ROOT, 'src/client/builtins/tab-icons.module.css'), 'utf8')
+    const classes = [...module.matchAll(/css\.([a-zA-Z]+)/g)].map(m => m[1])
+    expect(classes.length).toBeGreaterThan(0)
+    for (const name of new Set(classes)) expect(styles, name).toContain(`.${name}`)
+    // Every declaration that paints a color resolves to a token.
+    for (const declaration of styles.matchAll(/color:\s*([^;]+);/g)) {
+      expect(declaration[1], declaration[0]).toContain('var(--dsw-')
+    }
+  })
+
+  it('no icon dataset is shipped as a lazy chunk', () => {
+    const chunkDir = resolve(ROOT, 'src/client/chunks')
+    const chunks = readdirSync(chunkDir).filter(name => /\.tsx?$/.test(name))
+    for (const name of chunks) {
+      const source = readFileSync(resolve(chunkDir, name), 'utf8')
+      expect(source, name).not.toMatch(/#[0-9a-fA-F]{6}\b/)
     }
-    expect(offenders).toEqual([])
   })
 })