feat(admin): star/tags marks, service product-type filter, campaign bulk actions, SMTP test

- Star (is_starred) and colored tags for services, customers, orders, invoices:
  Markable trait, tags/taggables tables, PATCH administrator/marks/{type}/{key},
  tag CRUD, list filters starred / tag_ids[]
- GET administrator/services accepts product_type (falls back to product type
  for legacy rows without services.type)
- Mail campaigns: bulk cancel / retry failed / delete; cancelled campaigns are
  skipped by SendMailCampaignRecipient
- POST administrator/settings/test-smtp sends a test email through the saved
  mail transport

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

app/Models/MailCampaign.php

@@ -10,6 +10,12 @@ class MailCampaign extends Model
 {
     use HasFactory;
 
+    public const STATUS_CANCELLED = 'cancelled';
+
+    public const ACTIVE_STATUSES = ['queued', 'sending'];
+
+    public const FINISHED_STATUSES = ['completed', 'failed', self::STATUS_CANCELLED];
+
     protected $table = 'mail_campaigns';
 
     protected $fillable = [