Gradio API migration, training pipeline, news page, and UI improvements

- Migrate backend from REST API to Gradio @gradio/client for generation
- Fix Gradio parameter alignment (positions 36-49) for reference/cover audio
- Add LoRA training pipeline with dataset upload, preprocessing, and export
- Add News page with dismiss/restore and GitHub star button
- Add localization info icon in Settings language section
- Fix upload audio URL prefix, add missing MIME types
- Add training API routes and Python preprocess script
- Update i18n with news keys for all languages

components/Sidebar.tsx

@@ -1,5 +1,5 @@
 import React from 'react';
-import { Library, Disc, Search, User, LogIn, LogOut, Sun, Moon } from 'lucide-react';
+import { Library, Disc, Search, LogIn, LogOut, Sun, Moon, GraduationCap, Newspaper } from 'lucide-react';
 import { View } from '../types';
 import { useI18n } from '../context/I18nContext';
 
@@ -104,6 +104,21 @@ export const Sidebar: React.FC<SidebarProps> = ({
           onClick={() => onNavigate('search')}
           isExpanded={isOpen}
         />
+        <NavItem
+          icon={<GraduationCap size={20} />}
+          label={t('training')}
+          active={currentView === 'training'}
+          onClick={() => onNavigate('training')}
+          isExpanded={isOpen}
+        />
+        <NavItem
+          icon={<Newspaper size={20} />}
+          label={t('news')}
+          active={currentView === 'news'}
+          onClick={() => onNavigate('news')}
+          isExpanded={isOpen}
+        />
+
         <div className="mt-auto flex flex-col gap-2">
           {/* Theme Toggle */}
           <button