Update bundled OpenAPI spec to v2.165

Bumps docs/openapi.json from 2.160 to 2.165 so the Chat conversation
events reference page (GET /2/chat/conversations/{id}/events) resolves
and renders.

The replay endpoint moved out of account-activity in 2.165, so repoint
the account-activity create-replay-job page to the current
POST /2/webhooks/replay endpoint.

Author: tcaldwell-x