feat: Add a sort option for conversations waiting for a reply from an agent (#7364)

app/models/conversation.rb

@@ -15,6 +15,7 @@
 #  snoozed_until          :datetime
 #  status                 :integer          default("open"), not null
 #  uuid                   :uuid             not null
+#  waiting_since          :datetime
 #  created_at             :datetime         not null
 #  updated_at             :datetime         not null
 #  account_id             :integer          not null
@@ -45,6 +46,7 @@
 #  index_conversations_on_status_and_priority         (status,priority)
 #  index_conversations_on_team_id                     (team_id)
 #  index_conversations_on_uuid                        (uuid) UNIQUE
+#  index_conversations_on_waiting_since               (waiting_since)
 #
 
 class Conversation < ApplicationRecord
@@ -101,6 +103,7 @@ class Conversation < ApplicationRecord
 
   before_save :ensure_snooze_until_reset
   before_create :mark_conversation_pending_if_bot
+  before_create :ensure_waiting_since
 
   after_update_commit :execute_after_update_commit_callbacks
   after_create_commit :notify_conversation_creation
@@ -214,6 +217,10 @@ class Conversation < ApplicationRecord
     self.snoozed_until = nil unless snoozed?
   end
 
+  def ensure_waiting_since
+    self.waiting_since = Time.now.utc
+  end
+
   def validate_additional_attributes
     self.additional_attributes = {} unless additional_attributes.is_a?(Hash)
   end