fix: update NextAuth v5 configuration syntax

- Simplify NextAuth v5 beta configuration with direct export
- Remove intermediate variable assignment
- Addresses TypeScript compilation issues with NextAuth v5

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: jonphipps

apps/admin-portal/src/app/lib/auth.ts

@@ -1,8 +1,7 @@
 import NextAuth from "next-auth"
 import GitHub from "next-auth/providers/github"
-import type { NextAuthConfig } from "next-auth"
 
-const authOptions: NextAuthConfig = {
+export const { handlers, auth, signIn, signOut } = NextAuth({
   debug: process.env.NODE_ENV === "development",
   providers: [
     GitHub({
@@ -120,6 +119,4 @@ const authOptions: NextAuthConfig = {
       return `${baseUrl}/dashboard`;
     },
   },
-};
-
-export const { handlers, auth, signIn, signOut } = NextAuth(authOptions);
+});