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>

resources/views/filament/pages/auth/login.blade.php

@@ -0,0 +1,12 @@
+<x-filament-panels::page.simple>
+    <a
+        href="{{ route('auth.nextcloud') }}"
+        class="flex w-full items-center justify-center gap-3 rounded-lg px-4 py-3 text-sm font-semibold text-white shadow-sm transition hover:opacity-90"
+        style="background-color: #33ccff"
+    >
+        <svg class="h-5 w-5 shrink-0" viewBox="0 0 50 50" fill="currentColor" aria-hidden="true">
+            <path d="M25 2C12.3 2 2 12.3 2 25s10.3 23 23 23 23-10.3 23-23S37.7 2 25 2zm0 7a7 7 0 110 14 7 7 0 010-14zm0 32c-5.8 0-10.9-2.9-14-7.3.1-4.6 9.3-7.2 14-7.2s13.9 2.5 14 7.2C35.9 38.1 30.8 41 25 41z"/>
+        </svg>
+        Mit Blue Spices Zanzibar Cloud anmelden
+    </a>
+</x-filament-panels::page.simple>