refactor(captain): simplify reopen engagement check in Enterprise::Message

The respond_to?(:captain_assistant) guard was redundant — the enterprise
message override and the inbox concern defining the association are loaded
under the same enterprise gate, so the association always exists here.

enterprise/app/models/enterprise/message.rb

@@ -15,22 +15,16 @@ module Enterprise::Message
 
   private
 
-  # On reopen, a Captain inbox would normally re-pend the conversation for the bot. When the
-  # assistant won't engage (contact outside audience, or off-schedule), route to the human queue
-  # (open) instead of pending.
   def reopen_resolved_conversation
-    return conversation.open! if captain_should_not_engage?
+    captain_assistant = conversation.inbox.captain_assistant
+
+    return super if captain_assistant.blank?
+
+    return conversation.open! unless captain_assistant.engages?(conversation.contact, conversation)
 
     super
   end
 
-  def captain_should_not_engage?
-    inbox = conversation.inbox
-    inbox.respond_to?(:captain_assistant) &&
-      inbox.captain_assistant.present? &&
-      !inbox.captain_assistant.engages?(conversation.contact, conversation)
-  end
-
   def mark_pending_conversation_as_open_for_human_response
     return unless captain_pending_conversation?
     return unless human_response?