Implement internationalization (i18n) system for LoRA Manager

- Added i18n support with automatic language detection based on browser settings.
- Implemented translations for English (en) and Simplified Chinese (zh-CN).
- Created utility functions for text replacement in HTML templates and JavaScript.
- Developed a comprehensive translation key structure for various application components.
- Added formatting functions for numbers, dates, and file sizes according to locale.
- Included RTL language support and dynamic updates for DOM elements.
- Created tests to verify the functionality of the i18n system.

static/js/core.js

@@ -13,6 +13,7 @@ import { bannerService } from './managers/BannerService.js';
 import { showToast, initTheme, initBackToTop } from './utils/uiHelpers.js';
 import { initializeInfiniteScroll } from './utils/infiniteScroll.js';
 import { migrateStorageItems } from './utils/storageHelpers.js';
+import { i18n } from './i18n/index.js';
 
 // Core application class
 export class AppCore {
@@ -26,6 +27,10 @@ export class AppCore {
 
         console.log('AppCore: Initializing...');
         
+        // Initialize i18n first
+        window.i18n = i18n;
+        console.log(`AppCore: Language detected: ${i18n.getCurrentLocale()}`);
+        
         // Initialize managers
         state.loadingManager = new LoadingManager();
         modalManager.initialize();