feat: add job to remove stale contacts and contact_inboxes (#11186)

- Add a job to remove stale contacts and contact_inboxes across all accounts

Stale anonymous contact is defined as 
- have no identification (email, phone_number, and identifier are NULL)
- have no conversations
- are older than 30 days

---------

Co-authored-by: Pranav <pranav@chatwoot.com>
Co-authored-by: Shivam Mishra <scm.mymail@gmail.com>

app/services/internal/remove_stale_contacts_service.rb

@@ -0,0 +1,19 @@
+class Internal::RemoveStaleContactsService
+  pattr_initialize [:account!]
+
+  def perform(batch_size = 1000)
+    contacts_to_remove = @account.contacts.stale_without_conversations(30.days.ago)
+    total_deleted = 0
+
+    Rails.logger.info "[Internal::RemoveStaleContactsService] Starting removal of stale contacts for account #{@account.id}"
+
+    contacts_to_remove.find_in_batches(batch_size: batch_size) do |batch|
+      contact_ids = batch.map(&:id)
+
+      ContactInbox.where(contact_id: contact_ids).delete_all
+      Contact.where(id: contact_ids).delete_all
+      total_deleted += batch.size
+      Rails.logger.info "[Internal::RemoveStaleContactsService] Deleted #{batch.size} contacts (#{total_deleted} total) for account #{@account.id}"
+    end
+  end
+end