New callback events in Embed2

Three new events have been added to the subscribeEvent action in Embed2. With these events, you can provide a better experience after an AI Agent has handed the conversation off to a human agent:

Event key	Trigger
`ada:agent:joined`	Agent joined the conversation
`ada:agent:left`	Agent left the conversation
`ada:conversation:message`	End user received a message

If you’re using the Embed2 script, these events are immediately available. For the NPM package, update it to the latest version (1.7.17) to start using them.