feat(mail): implement MailService for tenant-specific SMTP configuration and update MailTestService to utilize it

database/seeders/EmailIntegrationSeeder.php

@@ -25,6 +25,7 @@ class EmailIntegrationSeeder extends Seeder
                     'MAIL_USERNAME' => 'required|email',
                     'MAIL_PASSWORD' => 'required|string',
                     'MAIL_FROM_ADDRESS' => 'required|email',
+                    'MAIL_FROM_NAME' => 'nullable|string|max:255',
                 ],
             ]
         );