feat(i18n): add internationalization support with i18next

- Add i18next and related dependencies for internationalization
- Implement language switcher component with English and Chinese support
- Create translation files for English and Chinese locales
- Update login and home pages to use translations
- Configure i18n initialization with language detection
- Add dayjs locale synchronization with i18n language changes
- Update tsconfig and eslint to ignore new locales directory
- Remove unused App.css and simplify index.css
- Update npmrc with mirror configuration

eslint.config.js

@@ -6,7 +6,7 @@ import tseslint from 'typescript-eslint'
 import { defineConfig, globalIgnores } from 'eslint/config'
 
 export default defineConfig([
-  globalIgnores(['dist']),
+  globalIgnores(['dist', 'rag_web_core']),
   {
     files: ['**/*.{ts,tsx}'],
     extends: [
@@ -19,5 +19,6 @@ export default defineConfig([
       ecmaVersion: 2020,
       globals: globals.browser,
     },
+    ignores: ['rag_web_core/**'],
   },
 ])