fix(i18n): complete Simplified Chinese core and plugin translations (#1542)

* fix(i18n): complete Chinese onboarding and navigation labels

* fix(i18n): translate remaining Chinese core and plugin interfaces

* fix(i18n): translate host editor tab overflow controls

* fix(i18n): use consistent Chinese fleet terminology

* fix(i18n): localize hardcoded controls and plugin views

* fix(i18n): translate built-in homepage widget catalog

* test(homepage): follow translated timezone placeholder

* fix(i18n): translate plugin-provided homepage widgets

* fix(i18n): localize feature settings section titles

plugins/homepage/tests/frontend/ClockTimezone.test.tsx

@@ -45,7 +45,9 @@ function renderForm(config: Partial<ClockConfig> = {}) {
   );
   return {
     onChange,
-    input: screen.getByPlaceholderText(/America\/New_York/) as HTMLInputElement,
+    input: screen.getByPlaceholderText(
+      "homepage.timezonePlaceholder",
+    ) as HTMLInputElement,
   };
 }