Add App\Rules\ReservedIdentifier for name + email local-part so users
cannot impersonate staff (admin, superadmin, support, root, takeone, …).
Separators are collapsed so "super_admin"/"super-admin"/"superadmin"
all match. Rule wired into RegisteredUserController@store.
email_verified_at is already absent from User::$fillable so only the
signed verification route can flip it — audited, no code change needed.
Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>
