feat(gui): settings panel with locale and theme preferences

Add the browser Settings surface as slot-composed plugins over new
preference services:

- Rename dsh-client-i18n to dsh-client-locale (locale is the domain
  name); LocaleService adds getLocale()/setLocale(id), immutable
  snapshots, a locale/change event, and dsh.locale persistence.
- ThemeService owns the light/dark/system preference (default system),
  resolves system via prefers-color-scheme, publishes theme/change
  snapshots, persists dsh.theme, and no longer touches the DOM;
  ui-layout's ThemePresenter applies resolved snapshots
  (body[data-ds-dark-theme] + alias tokens) and cleans up on dispose.
- ui-sidebar drops the phase-1 settings dropdown/modal; the foot renders
  the new sidebar.settings slot with the column state.
- New ui-settings shell occupies sidebar.settings: foot trigger row and
  the centered 1080x700 panel (figma 501:29947) with 24% mask, close
  button / mask click / Escape all closing, and a 188px nav projected
  from the settings.section list slot it declares. Nav labels are
  registrant-localized; sections re-register on locale change, so the
  ledger version is the shell's only subscription.
- ui-settings-general registers the General section: Permission and
  Tool Call skeletons, live Language (locale menu) and Appearance
  (Light/Dark/System cubes following the persisted preference); its
  slot store mirrors both service snapshots via apply-side listeners.
- ui-settings-models registers the Models nav entry with an empty
  content column.
- Portaled menus pin z-index above modal overlays (a menu anchored
  inside the settings dialog rendered underneath it and was
  unclickable).
- theme/data/list-pen icons in ui-primitives; settings copy ships as
  zh/en dictionaries; fixture manifests gain the settings rows.

packages/client/ui-layout/src/client/index.ts

@@ -4,13 +4,16 @@
  * four child slots (declaration = exclusive render authority), seats the
  * layout store (panel geometry), and wires the panel-action service face.
  * ctx.layout is the cross-plugin panel-action seam; navigation state lives
- * with the runtime sessions service.
+ * with the runtime sessions service. A second effect seats the theme
+ * presenter, which projects ctx.theme snapshots onto document.body.
  */
 import type { ClientContext } from '@deepseek-ai/dsh-client-runtime/client'
+import type {} from '@deepseek-ai/dsh-client-ui-theme/client'
 import type { PanelActions } from './service.ts'
 import { AppFrame } from './AppFrame.tsx'
 import { createLayoutStore } from './stores.ts'
 import { LayoutService } from './service.ts'
+import { ThemePresenter } from './theme-presenter.ts'
 
 // Contract surface only (export-convergence rule: cross-package consumers
 // keep a symbol exported; test-only/package-internal symbols live off /src).
@@ -62,7 +65,7 @@ export interface DetailsOwnerProps {}
 export interface EmptyOwnerProps { children?: never }
 
 /** Required services (cordis fiber inject — the loader passes the whole export surface as an object plugin). */
-export const inject = ['slots']
+export const inject = ['slots', 'theme']
 
 /**
  * Client plugin body: provide ctx.layout, then one register() call — AppFrame
@@ -98,4 +101,16 @@ export function apply(ctx: ClientContext): void {
       void disposeService()
     }
   }, 'ui-layout: service + root registration')
+
+  // Theme presentation: pure DOM writes from resolved snapshots — initial
+  // state through the getter once, then event-driven only; no React path.
+  ctx.effect(() => {
+    const presenter = new ThemePresenter()
+    presenter.apply(ctx.theme.getTheme())
+    const off = ctx.on('theme/change', snapshot => { presenter.apply(snapshot) })
+    return () => {
+      off()
+      presenter.dispose()
+    }
+  }, 'ui-layout: theme presenter')
 }

packages/client/ui-layout/src/client/theme-presenter.ts

@@ -0,0 +1,43 @@
+/**
+ * Global theme DOM applier: projects the resolved ThemeSnapshot onto
+ * document.body — the `data-ds-dark-theme` palette switch plus the active
+ * theme's alias-token overrides as inline CSS variables. Pure DOM writes, no
+ * React involvement; the presenter only ever retracts what it wrote itself,
+ * so foreign body attributes and inline styles survive apply/dispose.
+ */
+import type { ThemeSnapshot } from '@deepseek-ai/dsh-client-ui-theme/client'
+
+/** Body attribute selecting the dark base palette in the token stylesheets. */
+export const DARK_ATTRIBUTE = 'data-ds-dark-theme'
+
+/** Applies theme snapshots to document.body; one instance per plugin fiber. */
+export class ThemePresenter {
+  /** Token names this presenter wrote in the last apply (its retraction set). */
+  private appliedTokens: string[] = []
+
+  /**
+   * Project a snapshot onto the body: switch the palette attribute from
+   * `active.colorScheme` (never the id — `system` is resolved upstream) and
+   * replace the previously applied token variables with `active.tokens`.
+   * @param snapshot - resolved theme snapshot from ctx.theme.
+   */
+  apply(snapshot: ThemeSnapshot): void {
+    const body = document.body
+    if (snapshot.active.colorScheme === 'dark') body.setAttribute(DARK_ATTRIBUTE, '')
+    else body.removeAttribute(DARK_ATTRIBUTE)
+    for (const name of this.appliedTokens) body.style.removeProperty(name)
+    this.appliedTokens = []
+    for (const [name, value] of Object.entries(snapshot.active.tokens)) {
+      body.style.setProperty(name, value)
+      this.appliedTokens.push(name)
+    }
+  }
+
+  /** Retract everything this presenter wrote: the palette attribute and all applied token variables. */
+  dispose(): void {
+    const body = document.body
+    body.removeAttribute(DARK_ATTRIBUTE)
+    for (const name of this.appliedTokens) body.style.removeProperty(name)
+    this.appliedTokens = []
+  }
+}