Feature request: Zeron-managed child chat updates sent as messages (not tool outputs) #828

Right now, when the built-in MCP spins up child chats with wait: true / wait_for_turn, it kind of blocks the parent chat. We can prompt child agents to message the parent when they're done via send_message, but it's not really reliable since that session or harness can fail for any reason.

My idea is that we let create_chat / create_chats have the option of using Zeron itself to deliver lifecycle updates back to the parent as regular incoming messages. Two advantages here:

• The tool returns immediately. The main agent can finish the turn and go idle or do somthing else instead of waiting. It will receive incoming message when child work resolves.
• Even if a child chat errors out mid-run, Zeron knows about it and delivers the failure/error report to the parent.

The main chat could specify the mode of delivery too (queue vs steer, receive individual messages as each child finishes vs a single consolidated message with all results/errors).

I have a functional local vibecoded fork with a rough API like this.

// Example: kicking off a batch with message updates
{
  "requests": [
    { "project": "/repo", "prompt": "Audit auth routes" },
    { "project": "/repo", "prompt": "Audit DB migrations" }
  ],
  "notify": {
    "delivery": "queue",       // or "steer"
    "when": "all"              // or "each" for streaming individual updates
  }
}