refactor(settings): always-docked editor toolbar; reorder Navigation

The 'Always show editor toolbar' preference is gone — the docked
toolbar under the file tabs is now the only mode, and the floating
hover toolbar branch in the files editor (with its open-state and
outside-click machinery) is deleted. The stored preference is dropped
by a store migration and removed from desktop settings persistence,
settings search and every locale.

Navigation section order now reads: file editor keymap, auto-save,
terminal shell + login shell, Terminal Quick Keys, and the Session
tabs group last.

packages/ui/src/lib/settings/search.ts

@@ -148,13 +148,6 @@ const SETTINGS_SEARCH_ITEMS: readonly SettingsSearchItem[] = [
     descriptionKey: 'settings.openchamber.visual.field.autoSaveEnabledInfo',
     keywords: ['editor', 'autosave', 'auto-save', 'files', 'save'],
   },
-  {
-    id: 'appearance.expanded-editor-toolbar',
-    page: 'general',
-    titleKey: 'settings.openchamber.visual.field.expandedEditorToolbar',
-    keywords: ['editor', 'toolbar', 'tabs', 'docked', 'files'],
-    isAvailable: (ctx) => !ctx.isVSCode,
-  },
   {
     id: 'appearance.file-editor-keymap',
     page: 'general',