Restructure omni services and add Chatwoot research snapshot

research/chatwoot/app/services/contacts/bulk_assign_labels_service.rb

@@ -0,0 +1,19 @@
+class Contacts::BulkAssignLabelsService
+  def initialize(account:, contact_ids:, labels:)
+    @account = account
+    @contact_ids = Array(contact_ids)
+    @labels = Array(labels).compact_blank
+  end
+
+  def perform
+    return { success: true, updated_contact_ids: [] } if @contact_ids.blank? || @labels.blank?
+
+    contacts = @account.contacts.where(id: @contact_ids)
+
+    contacts.find_each do |contact|
+      contact.add_labels(@labels)
+    end
+
+    { success: true, updated_contact_ids: contacts.pluck(:id) }
+  end
+end