- Add required  field to PodcastCreateParams
- Restructure podcast_create POST body to use path + media.metadata
  shape (matching verified ABS API)
- Remove server_settings_get/update and session_list/delete tools
  (confirmed 404 on ABS v2.26.3)
- Note user CRUD endpoints require admin tokens (403 otherwise)
- Add 26 unit tests for podcast tools (URLs, query params, JSON bodies,
  schema validation, auth, error handling)
- Update README and API reference docs to reflect verified state