Fix tenant event form package selector so it no longer renders empty-value options, handles loading/empty

states, and pulls data from the authenticated /api/v1/tenant/packages endpoint.
    (resources/js/admin/pages/EventFormPage.tsx, resources/js/admin/api.ts)
  - Harden tenant-admin auth flow: prevent PKCE state loss, scope out StrictMode double-processing, add SPA
    routes for /event-admin/login and /event-admin/logout, and tighten token/session clearing semantics (resources/js/admin/auth/{context,tokens}.tsx, resources/js/admin/pages/{AuthCallbackPage,LogoutPage}.tsx,
    resources/js/admin/router.tsx, routes/web.php)

resources/js/admin/pages/LogoutPage.tsx

@@ -0,0 +1,19 @@
+import React from 'react';
+import { useAuth } from '../auth/context';
+import { ADMIN_PUBLIC_LANDING_PATH } from '../constants';
+
+export default function LogoutPage() {
+  const { logout } = useAuth();
+
+  React.useEffect(() => {
+    logout({ redirect: ADMIN_PUBLIC_LANDING_PATH });
+  }, [logout]);
+
+  return (
+    <div className="flex min-h-screen items-center justify-center bg-gradient-to-br from-rose-50 via-white to-slate-50 text-sm text-slate-600">
+      <div className="rounded-2xl border border-rose-100 bg-white/90 px-6 py-4 shadow-sm shadow-rose-100/60">
+        Abmeldung wird vorbereitet ...
+      </div>
+    </div>
+  );
+}