refactor(i18n): route command + settings manifest labels through the catalog (T-462)

Apply the manifest-i18n foundation across every extension: each
CommandContribution (45, command-palette + menu) gains titleKey + i18nNamespace,
and each SettingsCategory/section/field/option gains its key — with the English
text added to the owning extension's catalog. The settings renderer
(settings_category_view + settings_modal) threads the category's i18nNamespace
down and resolves every label/help/option through it; new catalogs created for
view, cli-install, keybindings-ui. No en_US behaviour change — the command
palette, menus, and settings panel now localize from the catalog (D-21).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/builtin/deeplink/src/extension.dart

@@ -24,7 +24,14 @@ class DeepLinkExtension extends ClideExtension {
 
   @override
   List<ContributionPoint> get contributions => [
-    CommandContribution(id: 'deeplink.invoke', command: 'deeplink.invoke', title: 'Open a clide:// deep link', run: _invoke),
+    CommandContribution(
+      id: 'deeplink.invoke',
+      command: 'deeplink.invoke',
+      title: 'Open a clide:// deep link',
+      titleKey: 'command.deeplink.invoke',
+      i18nNamespace: id,
+      run: _invoke,
+    ),
   ];
 
   @override