Adds a Subagent orchestration section to AGENTS.md so orchestrating
agents know upfront: forks must stop once their assigned task is done
rather than autonomously draining a shared TaskList, governance-gated
actions must not be exposed to forks without a fresh confirmation
round, and TaskGet/TaskUpdate/TaskList are fork-only so the coordinator
must own task-list bookkeeping for fresh subagents itself.
Refs #68, #70
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FNJWdVvdgvZCHi1hZGqgVQ
