feat(mail): introduce MailService for tenant-specific SMTP handling and update related tests

app/Domains/MailTest/Services/MailTestService.php

@@ -2,8 +2,7 @@
 
 namespace App\Domains\MailTest\Services;
 
-use App\Domains\Mail\Services\MailService;
-use App\Domains\MailTest\Mailables\TestMail;
+use App\Domains\Integration\Services\MailService;
 use App\Domains\Tenant\Models\Tenant;
 
 class MailTestService
@@ -16,8 +15,13 @@ class MailTestService
         $subject ??= 'Prueba de correo de Shopit';
         $message ??= 'Este es un correo de prueba enviado desde Shopit.';
 
-        $mailService = new MailService($tenant);
-        $mailService->send($recipient, new TestMail($subject, $message, $tenant));
+        $mailService = (new MailService)->forTenant($tenant->codigo);
+        $mailService->send(
+            $recipient,
+            $subject,
+            '<h1 style="margin: 0 0 20px;">'.e($subject).'</h1>'
+                .'<p>'.nl2br(e($message)).'</p>',
+        );
 
         return [
             'message' => 'Correo de prueba enviado correctamente.',