Pin the UI locale to the language setting and add theme + language selectors with a dark palette

src/main/database/migrations/048-ui-preferences.ts

@@ -0,0 +1,10 @@
+/**
+ * App-level UI preferences on the single app_state row. Theme drives the
+ * renderer palette; language pins Chromium's UI locale (form-control strings
+ * were following the OS locale and leaking Chinese into the English UI, so
+ * the default is English rather than system).
+ */
+export const uiPreferencesSchema = `
+  alter table app_state add column theme text not null default 'system';
+  alter table app_state add column language text not null default 'en';
+`;