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_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;
 }