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)

app/Http/Controllers/Auth/RegisteredUserController.php

@@ -102,7 +102,9 @@ class RegisteredUserController extends Controller
         event(new Registered($user));
 
         // Send Welcome Email
-        Mail::to($user)->queue(new \App\Mail\Welcome($user));
+        Mail::to($user)
+            ->locale($user->preferred_locale ?? app()->getLocale())
+            ->queue(new \App\Mail\Welcome($user));
 
         if ($request->filled('package_id')) {
             $package = \App\Models\Package::find($request->package_id);