Replace login form with single Nextcloud OAuth button

Removes email/password fields entirely; custom login page shows only
the blue "Mit Blue Spices Zanzibar Cloud anmelden" button.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/Filament/Pages/Auth/Login.php

@@ -0,0 +1,13 @@
+<?php
+
+namespace App\Filament\Pages\Auth;
+
+use Filament\Pages\Auth\Login as BaseLogin;
+
+class Login extends BaseLogin
+{
+    public function getView(): string
+    {
+        return 'filament.pages.auth.login';
+    }
+}