Real production test (user account) confirmed HM->AM POST /agents creates a real
agent (returned subdomain + status). But stop/delete still used the old
/api/agent/agents/{id} defaults and 404'd. Aligned status/stop/delete defaults to
the same namespace as create: /agents/{id}, /agents/{id}/stop. AM contract doc
notes these are HM's best guess pending AM's confirmation of the real lifecycle
endpoints (their doc only specified create).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>