[Bug]: Antigravity (agy) sessions show Idle while they are running

## Summary

Orca does not correctly reflect the running status of Antigravity CLI (`agy`) sessions. The UI shows `Idle` while the underlying session is still running.

## Steps to reproduce

1. Start an Antigravity CLI (`agy`) session in Orca.
2. Keep the session running.
3. Check its status in the workspace or session list.

## Actual behavior

The session is shown as `Idle` even though it is still running. The UI shows two `agy` sessions with the `Idle` status.

## Expected behavior

A running `agy` session should be shown as `Running`, and status transitions should remain synchronized with the actual agent lifecycle.

## Suspected cause

The `agy` lifecycle/status hooks may not be wired into Orca's status tracking, or the running/idle event mapping may be incomplete. This is a hypothesis for investigation.

## Environment

- Orca version: 1.4.198
- OS: macOS

Start by reproducing an Antigravity CLI (agy) session in Orca and trace the lifecycle/status handling in the TypeScript code. Confirm how running and idle events are mapped, then verify that the workspace and session list show Running during execution and remain synchronized through status transitions.

Written by the indexing model from the issue text.