refactor(i18n): route remaining extension labels through the catalog (T-468)

Migrate the user-facing strings in menubar, output, search, deeplink, editor,
files, terminal, markdown, and vim to ClideSettings.i18n.string/.interpolated;
extend the existing catalogs and create the missing ones (deeplink, output,
search, markdown, menubar, vim). vim mode labels now resolve through
builtin.vim (default still `-- NORMAL --`, now localizable). A dock-status test
seeds builtin.output so the widget's own i18n lookups resolve instead of
warning into the logRing it counts. No en_US behaviour change (D-21).

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

lib/builtin/vim/src/vim_mode_indicator.dart

@@ -17,14 +17,11 @@ class VimModeIndicator extends StatelessWidget {
       builder: (context, _) {
         if (!service.enabled) return const SizedBox.shrink();
         final tokens = ClideSettings.theme.of(context).surface;
+        final mode = service.mode;
+        final label = ClideSettings.i18n.string(context, 'mode.${mode.name}', namespace: 'builtin.vim', placeholder: mode.label);
         return Padding(
           padding: const EdgeInsets.symmetric(horizontal: 8),
-          child: ClideText(
-            '-- ${service.mode.label} --',
-            fontFamily: ClideSettings.fonts.monoOf(context),
-            fontSize: clideFontCaption,
-            color: tokens.statusBarForeground,
-          ),
+          child: ClideText('-- $label --', fontFamily: ClideSettings.fonts.monoOf(context), fontSize: clideFontCaption, color: tokens.statusBarForeground),
         );
       },
     );

lib/builtin/vim/src/vim_mode_service.dart

@@ -31,8 +31,9 @@ enum VimMode {
   /// The keymap scope flag set true exactly when this mode is active.
   final String scopeFlag;
 
-  /// Status-bar label, shown as `-- NORMAL --` (Vim's own vocabulary;
-  /// intentionally untranslated, like Vim itself).
+  /// English status-bar label, shown as `-- NORMAL --`. Used as the i18n
+  /// placeholder for `mode.<name>` in the builtin.vim catalog (T-462); the
+  /// default keeps Vim's own vocabulary, but a locale may override it.
   final String label;
 }