fix invitations not being respected during signup when email case differs

app/Service/InvitationService.php

@@ -23,6 +23,10 @@ class InvitationService
      */
     public function inviteUser(Organization $organization, string $email, Role $role, User $inviter): OrganizationInvitation
     {
+        // Normalize the email so it matches how user emails are stored (see UserService::createUser),
+        // otherwise a mixed-case invite silently fails to link on registration.
+        $email = strtolower($email);
+
         if (app(MemberService::class)->isEmailAlreadyMember($organization, $email)) {
             throw new UserIsAlreadyMemberOfOrganizationApiException;
         }
@@ -55,7 +59,7 @@ class InvitationService
         $organizations = new Collection;
 
         $invitations = OrganizationInvitation::query()
-            ->where('email', $user->email)
+            ->whereRaw('lower(email) = ?', [strtolower($user->email)])
             ->whereNotNull('accepted_at')
             ->get();