Remove the '[AO] Worker <id> has gone idle' nudge messages sent to the orchestrator

[harshitsinghbhandari]

The daemon auto-sends messages like this to the orchestrator session whenever a worker goes idle:

[AO] Worker agent-orchestrator-69 ("release-arch-spec") has gone idle and may be done. Inspect it with ao session get ..., then report its status and any PR to the human. If it needs more work, redirect it with ao send.

These are unnecessary and should be removed:

• They re-fire repeatedly for the same worker (the same session gets nudged multiple times, including ones already inspected and reported).
• Idle does not mean done; read-only/research workers idle immediately after reporting, so the nudge adds no signal.
• Each nudge burns an orchestrator turn and context on boilerplate the human can already see in the sidebar (idle state is visible there).

Just drop the nudge. The orchestrator inspects workers on demand; the human sees idle state in the UI.