feat: Bulk delete for contacts (#12778)

Introduces a new bulk action `delete` for contacts

ref: https://github.com/chatwoot/chatwoot/pull/12763

## Screens

<img width="1492" height="973" alt="Screenshot 2025-10-31 at 6 27 21 PM"
src="https://github.com/user-attachments/assets/30dab1bb-2c2c-4168-9800-44e0eb5f8e3a"
/>
<img width="1492" height="985" alt="Screenshot 2025-10-31 at 6 27 32 PM"
src="https://github.com/user-attachments/assets/5be610c4-b19e-4614-a164-103b22337382"
/>

app/services/contacts/bulk_delete_service.rb

@@ -0,0 +1,18 @@
+class Contacts::BulkDeleteService
+  def initialize(account:, contact_ids: [])
+    @account = account
+    @contact_ids = Array(contact_ids).compact
+  end
+
+  def perform
+    return if @contact_ids.blank?
+
+    contacts.find_each(&:destroy!)
+  end
+
+  private
+
+  def contacts
+    @account.contacts.where(id: @contact_ids)
+  end
+end