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).

src/client/native/index.ts

@@ -162,7 +162,7 @@ export function registerNativeSurface(deps: NativeSurfaceDeps): () => void {
       ctx.slots.inject('sidebar.right.pane.tab.title', () => ctx.slots.register({
         name: 'sidebar.right.pane.tab.title',
         key: id,
-        inject: () => ({ records }),
+        inject: () => ({ records, service, descriptorId: injected.descriptorId }),
       }, NativeTabTitle)),
     ]
 

src/client/native/tab-adapter.tsx

@@ -31,6 +31,12 @@ import type { BetterSidebarService } from '../service.ts'
 import type { SidebarStore, SidebarTab, TabType } from '../state.ts'
 import css from '../sidebar.module.css'
 
+/** The chip glyph's size: the tab strip's own icon scale. */
+const CHIP_ICON_SIZE = 14
+
+/** The editor kind: a chip for a file row shows the file's own glyph. */
+const EDITOR_KIND = 'editor'
+
 /**
  * The plugin-side seed a native open carries in `navigation.params`.
  * JSON-shaped by convention (the native surface does not validate it).
@@ -330,20 +336,52 @@ export function NativeTabBody(props: NativeBodyInjected & NativeBodyFrameworkPro
 /** What a title registration injects. */
 export interface NativeTitleInjected {
   readonly records: NativeTabRecords
+  readonly service: BetterSidebarService
+  /** The descriptor id this title belongs to (one registration per descriptor). */
+  readonly descriptorId: string
 }
 
 /**
- * A live tab chip: the synthetic record's title (the editor rewrites it on an
- * in-place file switch, the side chat on the thread's first prompt). Without
- * this registration the chip would keep the title captured when the tab
- * opened.
+ * A live tab chip: the type's glyph followed by the synthetic record's title
+ * (the editor rewrites it on an in-place file switch, the side chat on the
+ * thread's first prompt). Without this registration the chip would keep the
+ * title captured when the tab opened.
+ *
+ * The host's tab definition has no icon field — a chip is drawn from the
+ * `title` text alone — but this slot IS the chip's content, so the glyph is
+ * ours to add. Placement follows the plugin's own semantics: an editor tab
+ * with a path shows that file's icon (the same glyph the tree row shows), and
+ * every other tab shows its descriptor's icon. Both ride
+ * `descriptor.icon`, so the workbench strip, the guide capsules and the chip
+ * cannot drift apart.
  */
 export function NativeTabTitle(props: NativeTitleInjected & NativeBodyFrameworkProps): ReactNode {
-  const { records, useTabInfo } = props
+  const { records, service, descriptorId, useTabInfo } = props
   const nativeTab = useTabInfo().tab
-  return useSyncExternalStore(
+  const version = useSyncExternalStore(
     listener => records.subscribe(listener),
-    () => records.get(nativeTab.id)?.tab.title ?? nativeTab.title,
+    () => records.versionOf(nativeTab.id),
+  )
+  const record = records.get(nativeTab.id)
+  const title = record?.tab.title ?? nativeTab.title
+  // `version` is read so a title/path/meta mutation re-renders the chip; the
+  // icon itself is derived from the record, never stored.
+  void version
+  const descriptor = service.getTab(descriptorId) ?? service.getTab(record?.tab.type ?? nativeTab.kind)
+  const path = record?.tab.path
+  const icon = path !== undefined && descriptorId === EDITOR_KIND
+    ? service.fileIcon(path, CHIP_ICON_SIZE)
+    : undefined
+  const glyph = icon ?? (typeof descriptor?.icon === 'function'
+    ? descriptor.icon(CHIP_ICON_SIZE)
+    : descriptor?.icon)
+  if (glyph === undefined || glyph === null) return title
+  return (
+    <>
+      {/* Decorative: the chip's accessible name stays the title. */}
+      <span className={css.chipIcon} aria-hidden="true">{glyph}</span>
+      {title}
+    </>
   )
 }