chore: remove next-auth, use simple auth

app/api/auth/[...nextauth]/route.ts

@@ -1,2 +1,9 @@
-import { handlers } from '@/lib/auth'
-export const { GET, POST } = handlers
+import { NextResponse } from 'next/server'
+
+// NextAuth kaldırıldı
+export async function GET() {
+  return NextResponse.json({ error: 'Not found' }, { status: 404 })
+}
+export async function POST() {
+  return NextResponse.json({ error: 'Not found' }, { status: 404 })
+}