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/Http/Resources/Api/Admin/InvoiceResource.php

@@ -32,6 +32,8 @@ class InvoiceResource extends JsonResource
             'amount_paid'     => (int) $this->amount_paid,
             'outstanding'     => \App\Services\InvoicePaymentService::outstanding($this->resource),
             'status'          => $this->status,
+            'is_starred' => (bool) $this->is_starred,
+            'tags'       => $this->whenLoaded('tags'),
             'due_date'        => $this->due_date,
             'paid_at'         => $this->paid_at,
             'reminder_step'   => (int) $this->reminder_step,