Fix serialization mismatch for project/domain fields in Mail and Certificate messages

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/Appwrite/Event/Message/Certificate.php

@@ -21,8 +21,8 @@ readonly class Certificate extends Base
     public function toArray(): array
     {
         return [
-            'project' => $this->project,
-            'domain' => $this->domain,
+            'project' => $this->project?->getArrayCopy(),
+            'domain' => $this->domain?->getArrayCopy(),
             'skipRenewCheck' => $this->skipRenewCheck,
             'validationDomain' => $this->validationDomain,
             'action' => $this->action,

src/Appwrite/Event/Message/Mail.php

@@ -26,7 +26,7 @@ readonly class Mail extends Base
     public function toArray(): array
     {
         return [
-            'project' => $this->project,
+            'project' => $this->project?->getArrayCopy(),
             'recipient' => $this->recipient,
             'name' => $this->name,
             'subject' => $this->subject,