- Introduce SearchAttributesManager and new tctl admin/cluster commands to add and list custom search attributes (add‑only, auto‑populate on server start).
- Update Docker image behavior: server image no longer auto‑creates the Elasticsearch index; index must be created manually unless using auto‑setup image or Helm chart, and remove predefined Custom Field search attributes from default config.
- Add priority‑based API throttling, propagate metrics across services, and include numerous bugfixes (e.g., history metrics double‑emit, sticky task queue reset, namespace ack level calculation).