New 'Custom OpenAI-compatible' and 'Custom Anthropic-compatible' providers let
an agent run against any compatible endpoint by base URL + key: the turn posts
Chat Completions (/chat/completions) or Anthropic Messages (/v1/messages) at the
configured base URL. Backfilled into existing orgs by migration 037.
Closes the Anthropic OAuth gap with a native Claude Pro/Max device sign-in
(reusing the OAuth engine) and adds three OpenAI-compatible API-key
providers. Model lists are sourced from the provider registry. A backfill
migration seeds the new providers into existing organizations idempotently.
ZacharyZhang-NY