Add Turkish (tr) to client i18n and language registry

* feat(i18n): add Turkish language support and base tr translations

Agent-Logs-Url: https://github.com/SkyLostTR/TREK/sessions/f86511d9-8ff1-4459-8ec1-879936135741

Co-authored-by: SkyLostTR <21984261+SkyLostTR@users.noreply.github.com>

* test(i18n): update language list expectations for Turkish support

client/src/i18n/TranslationContext.tsx

@@ -6,6 +6,7 @@ import es from './translations/es'
 import fr from './translations/fr'
 import hu from './translations/hu'
 import it from './translations/it'
+import tr from './translations/tr'
 import ru from './translations/ru'
 import zh from './translations/zh'
 import zhTw from './translations/zhTw'
@@ -23,7 +24,7 @@ type TranslationStrings = Record<string, string | { name: string; category: stri
 
 // Keyed by SupportedLanguageCode so TypeScript enforces all languages have a translation.
 const translations: Record<SupportedLanguageCode, TranslationStrings> = {
-  de, en, es, fr, hu, it, ru, zh, 'zh-TW': zhTw, nl, id, ar, br, cs, pl,
+  de, en, es, fr, hu, it, tr, ru, zh, 'zh-TW': zhTw, nl, id, ar, br, cs, pl,
 }
 
 // Derived from SUPPORTED_LANGUAGES — add new languages there, not here.
@@ -38,7 +39,7 @@ export function getLocaleForLanguage(language: string): string {
 
 export function getIntlLanguage(language: string): string {
   if (language === 'br') return 'pt-BR'
-  return ['de', 'es', 'fr', 'hu', 'it', 'ru', 'zh', 'zh-TW', 'nl', 'ar', 'cs', 'pl', 'id'].includes(language) ? language : 'en'
+  return ['de', 'es', 'fr', 'hu', 'it', 'tr', 'ru', 'zh', 'zh-TW', 'nl', 'ar', 'cs', 'pl', 'id'].includes(language) ? language : 'en'
 }
 
 export function isRtlLanguage(language: string): boolean {

client/src/i18n/supportedLanguages.ts

@@ -12,6 +12,7 @@ export const SUPPORTED_LANGUAGES = [
   { value: 'zh',    label: '简体中文',              locale: 'zh-CN' },
   { value: 'zh-TW', label: '繁體中文',              locale: 'zh-TW' },
   { value: 'it',    label: 'Italiano',             locale: 'it-IT' },
+  { value: 'tr',    label: 'Türkçe',               locale: 'tr-TR' },
   { value: 'ar',    label: 'العربية',              locale: 'ar-SA' },
   { value: 'id',    label: 'Bahasa Indonesia',     locale: 'id-ID' },
 ] as const