Add skip_notifications to conversations reply endpoint

Adds support for the skip_notifications parameter on the Conversations API
reply endpoint (POST /conversations/{id}/reply) in the unstable spec.

This brings parity with the Tickets API which already supports this parameter.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: markdennis22

descriptions/0/api.intercom.io.yaml

@@ -15723,6 +15723,10 @@ components:
           items:
             "$ref": "#/components/schemas/conversation_attachment_files"
           maxItems: 10
+        skip_notifications:
+          type: boolean
+          description: Option to disable notifications when replying to a conversation.
+          example: true
       required:
       - message_type
       - type