feat: Add job to remove stale contact inboxes (#8096)

app/models/contact_inbox.rb

@@ -33,6 +33,13 @@ class ContactInbox < ApplicationRecord
 
   has_many :conversations, dependent: :destroy_async
 
+  # contact_inboxes that are not associated with any conversation
+  scope :stale_without_conversations, lambda { |time_period|
+    left_joins(:conversations)
+      .where('contact_inboxes.created_at < ?', time_period)
+      .where(conversations: { contact_id: nil })
+  }
+
   def webhook_data
     {
       id: id,