transform admin panel with comprehensive professional UI

- migrate from SQLite to PostgreSQL with Drizzle ORM
- implement comprehensive AdminLayout with expandable sidebar navigation
- create professional dashboard with real-time charts and metrics
- add advanced monitoring, reporting, and export functionality
- fix menu alignment and remove non-existent pages
- eliminate duplicate headers and improve UI consistency
- add Tailwind CSS v3 for professional styling
- expand database schema from 6 to 15 tables
- implement role-based access control and API key management
- create comprehensive settings, monitoring, and system info pages

pages/_app.tsx

@@ -1,4 +1,5 @@
 import type { AppProps } from 'next/app'
+import '../styles/globals.css'
 
 export default function App({ Component, pageProps }: AppProps) {
   return <Component {...pageProps} />