feat(ui): modern shadcn/ui theme with violet accent across all pages

Add shadcn/ui (Radix + Tailwind 4) components, zinc/violet theme tokens and self-hosted Inter. New header with user menu, Steam cover art, skeletons and toasts. Replace @mdi/font with lucide-react. Fix: top-owned list on the landing page only showed with top-played entries; numbers use the app language.

src/main.jsx

@@ -5,7 +5,6 @@ import App from './App.jsx';
 import {PreferencesProvider} from './context/PreferencesContext.jsx';
 import './i18n';
 import './style.css';
-import '@mdi/font/css/materialdesignicons.css';
 
 createRoot(document.getElementById('root')).render(
     <StrictMode>