feat(tui/remote): live monitoring for sub-agent progress, tools, and outputs #5

Problem

If multiple sub-agents are running, users need visibility into what each one is doing in real time.

Goal

Add a monitoring layer that exposes per-agent status, progress, current tool activity, and completion state.

Expected UX

• TUI panel/dashboard for active sub-agents
• optional remote/web stream for browser-based monitoring
• per-agent status:
  • queued
  • running
  • waiting
  • done
  • failed

Requirements

• structured event stream per sub-agent
• current action/tool visibility
• files changed summary
• durable event log for replay/debugging

Event examples

• agent_started
• tool_start
• tool_end
• progress
• file_changed
• agent_done
• agent_failed

Likely implementation areas

• src/agent_core.rs
• src/remote.rs
• src/remote_channel.rs
• TUI monitoring components

Acceptance criteria

• user can see all active sub-agents
• user can inspect one agent’s recent actions
• completion/failure is clearly surfaced
  EOF