Add admin customer edit, status management, and admin notes

Adds edit/update endpoints for customer management with admin notes
field, form request validation, status change audit logging, and
8 new tests (171 total, 846 assertions).

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

website/app/Models/User.php

@@ -28,6 +28,7 @@ class User extends Authenticatable implements MustVerifyEmail
         'status',
         'phone',
         'company',
+        'admin_notes',
     ];
 
     /** @var list<string> */