Document the T-462 i18n architecture: ext-id namespaces auto-loaded on activation, a 'core' catalog for framework chrome, the null-safe ClideSettings.i18n read facade, contribution titleKey/labelKey fields, and the assets/i18n/<locale>/<namespace>.json locale-dir layout. Add the "route user-facing strings through the catalog" rule to the ui-design skill. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>