v0.14.6

Adds independent native event retention to `POST /run`.

- `eventMode` is now the event-retention control: `full` returns untouched
  provider records in the stable `{sequence, attempt, backend, eventType,
  event}` envelope, while `none` omits them. `auto` preserves the previous
  schema and `json-verbose` compatibility behaviour.
- Structured JSON, session metadata, usage, retry attempts, and raw output
  remain independent from event retention. Schema retries retain records from
  every attempt when events are enabled.
- Corrects `/openai/v1/*` route references and the OpenAI adapter's capability
  documentation. Adds unit coverage for the public event response contract.