fix(i18n): add i18n support for custom model feature in ModelSelector (#172)

* feat(models): add custom model name input with provider selector

- Add custom model input field at bottom of model selector modal
- Add provider dropdown to specify target provider for custom model
- Track custom models in app store and display with CUSTOM badge
- Merge custom model into provider group list
- Fix custom provider models being overwritten by API response (keep both)

* Upload screenshot

* fix(i18n): add i18n support for custom model feature in ModelSelector

Replace hardcoded English strings (CUSTOM badge, placeholder, hint) with
vue-i18n t() calls and add corresponding translation keys to all 8 locales
(en, zh, ja, ko, fr, es, de, pt).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: toller892 <892@users.noreply.github.com>
Co-authored-by: Tony <125938283+toller892@users.noreply.github.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

packages/client/src/i18n/locales/ko.ts

@@ -252,6 +252,9 @@ export default {
     nousApproved: '로그인 성공',
     nousDenied: '인증이 거부되었습니다',
     nousExpired: '인증이 만료되었습니다',
+    customBadge: '커스텀',
+    customModelPlaceholder: '사용자 지정 모델 이름',
+    customModelHint: 'Enter로 불러오기',
     noProviders: 'Provider가 없습니다. 사용자 지정 Provider를 추가하여 시작하세요.',
     builtIn: '내장',
     customType: '사용자 지정',