Create agent - SeaOtter

Creates an agent and enqueues async provision. Returns immediately with status=provisioning.

curl -sS -X POST "$SEAOTTER_API/api/v1/agents" \
  -H "Authorization: Bearer $SEAOTTER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"name":"first-hermes","resource_plan":"starter"}'

Poll GET /api/v1/agents/{id} and inspect config.provisioning_stages. See Provisioning lifecycle. Hard provision failures may surface as 503 so Cloud Tasks retries.