fix(portal): NextAuth redirect loop and production NEXTAUTH_URL docs

- Remove pages.signIn pointed at API route; normalize redirects for LAN callbacks
- signIn callbackUrl /; auth error page Try Again to /
- Add .env.example; README documents public NEXTAUTH_URL (sankofa.nexus)

Made-with: Cursor

portal/src/app/api/auth/error/page.tsx

@@ -35,7 +35,7 @@ function AuthErrorContent() {
             Go Home
           </Link>
           <Link
-            href="/api/auth/signin"
+            href="/"
             className="px-6 py-3 bg-gray-600 text-white rounded-lg hover:bg-gray-700 transition-colors inline-block"
           >
             Try Again

portal/src/app/page.tsx

@@ -10,9 +10,9 @@ export default function Home() {
 
   if (status === 'loading') {
     return (
-      <div className="flex min-h-screen items-center justify-center bg-gray-900">
+      <div className="flex min-h-screen items-center justify-center bg-gray-950 px-4">
         <div className="text-center">
-          <div className="mb-4 h-8 w-8 animate-spin rounded-full border-4 border-gray-300 border-t-blue-600 mx-auto"></div>
+          <div className="mx-auto mb-4 h-8 w-8 animate-spin rounded-full border-4 border-gray-600 border-t-orange-500" />
           <p className="text-gray-400">Loading...</p>
         </div>
       </div>
@@ -21,19 +21,25 @@ export default function Home() {
 
   if (status === 'unauthenticated') {
     return (
-      <div className="flex min-h-screen items-center justify-center bg-gray-900">
-        <div className="text-center max-w-md mx-auto p-8">
-          <h1 className="text-2xl font-bold text-white mb-4">Welcome to Portal</h1>
-          <p className="text-gray-400 mb-6">Please sign in to continue</p>
+      <div className="flex min-h-screen flex-col items-center justify-center bg-gray-950 px-4 py-12">
+        <div className="w-full max-w-md rounded-2xl border border-gray-800 bg-gray-900/80 p-8 shadow-xl shadow-black/40 backdrop-blur-sm">
+          <p className="mb-1 text-center text-sm font-medium uppercase tracking-wide text-orange-400">
+            Sankofa Phoenix
+          </p>
+          <h1 className="mb-2 text-center text-2xl font-bold text-white">Welcome to Portal</h1>
+          <p className="mb-8 text-center text-gray-400">Sign in to open Nexus Console.</p>
           <button
-            onClick={() => signIn()}
-            className="px-6 py-3 bg-blue-600 text-white rounded-lg hover:bg-blue-700 transition-colors"
+            type="button"
+            onClick={() => signIn(undefined, { callbackUrl: '/' })}
+            className="w-full rounded-lg bg-gradient-to-r from-orange-500 to-amber-500 px-6 py-3 font-semibold text-gray-950 shadow-lg transition hover:from-orange-400 hover:to-amber-400 focus:outline-none focus:ring-2 focus:ring-orange-400 focus:ring-offset-2 focus:ring-offset-gray-900"
           >
             Sign In
           </button>
-          <p className="text-sm text-gray-500 mt-4">
-            Development mode: Use any email/password
-          </p>
+          {process.env.NODE_ENV === 'development' && (
+            <p className="mt-6 text-center text-xs text-gray-500">
+              Development: use any email/password with your dev IdP configuration.
+            </p>
+          )}
         </div>
       </div>
     );