Native Live Dashboard reporting — built-in heartbeat and step events

[jadercorrea]

Problem

CLI currently has a live.Client but SendSessionEvent is not wired up (manager.go:132 lint error). Agents must manually report via curl/workflow.

Solution

Wire live.Client into the main run/chat loop to automatically:

• POST /api/report/connect on startup (with engine=cli, context, task)
• POST /api/report/step on each task_boundary change
• Periodic heartbeat every 10s to keep RUNNING status
• POST /api/report/disconnect on clean exit / Ctrl+C

Acceptance Criteria

• Fix SendSessionEvent lint — wire method properly
• CLI auto-reports to Live Dashboard when GPTCODE_LIVE_URL is set
• No workflow/curl needed — zero-config reporting
• Heartbeat keeps agent RUNNING (no false stale)
• Clean disconnect on exit