feat: Upgrade to Next.js 16.1 & React 19.2, migrate to Supabase SSR with async client handling

src/app/admin/page.tsx

@@ -1,13 +1,12 @@
 export const dynamic = 'force-dynamic';
-import { createServerComponentClient } from '@supabase/auth-helpers-nextjs';
-import { cookies } from 'next/headers';
+import { createClient } from '@/lib/supabase/server';
 import { redirect } from 'next/navigation';
 import { checkIsAdmin, getGlobalApiStats } from '@/services/track-api-usage';
 import { BarChart3, TrendingUp, Users, Calendar, AlertCircle } from 'lucide-react';
 import Link from 'next/link';
 
 export default async function AdminPage() {
-    const supabase = createServerComponentClient({ cookies });
+    const supabase = await createClient();
     const { data: { user } } = await supabase.auth.getUser();
 
     console.log('[Admin Page] User:', user?.id, user?.email);