feat(translator): add Urdu as a Translate Text target language (#4721) (#4726)

Add Urdu (ur) to TRANSLATOR_LANGS so it appears in the Translate Text
language list (inline TranslatorPopup and Settings → Translation). The
list is not provider-gated, and Google/Azure/Yandex all translate to
Urdu; Urdu is already in MIGHT_BE_RTL_LANGS so the translated output
renders right-to-left.

Closes #4721

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

apps/readest-app/src/__tests__/services/constants.test.ts

@@ -1109,6 +1109,10 @@ describe('services/constants', () => {
       expect(TRANSLATOR_LANGS['fi']).toBeDefined();
     });
 
+    it('TRANSLATOR_LANGS includes Urdu', () => {
+      expect(TRANSLATOR_LANGS['ur']).toBe('اردو');
+    });
+
     it('SUPPORTED_LANGS includes zh in addition to TRANSLATED_LANGS entries', () => {
       expect(typeof SUPPORTED_LANGS).toBe('object');
       expect(SUPPORTED_LANGS['zh']).toBeDefined();

apps/readest-app/src/services/constants.ts

@@ -958,6 +958,7 @@ export const TRANSLATOR_LANGS: Record<string, string> = {
   sl: 'Slovenščina',
   sk: 'Slovenčina',
   fa: 'فارسی',
+  ur: 'اردو',
 };
 
 export const SUPPORTED_LANGS: Record<string, string> = { ...TRANSLATED_LANGS, zh: '中文' };