Connection Events - Mint Starter Kit

These events are sent when a streaming connection is established.

`CONNECTION_ESTABLISHED`

Emitted immediately after the SSE connection is set up.

{
  "type": "CONNECTION_ESTABLISHED",
  "eventId": "evt_1",
  "threadId": "thread_456",
  "requestId": "req_1",
  "eventMessage": {
    "agent": null,
    "content": "",
    "collaborationId": null,
    "activeAssistantCollaborationRequired": null,
    "toolExecutionApprovalRequest": null,
    "timestamp": "2025-08-12T00:00:00"
  }
}