chore: refresh spec — Pydantic discriminated unions for auth + check details

Picks up the upstream @devhelm/openapi-tools update that inlines
discriminator subtypes and rewrites parents as oneOf+discriminator. The
generated Pydantic models now use:

  type: Literal["bearer"]   (and "basic", "header", "api_key")
  check_type: Literal["http"]   (and "tcp", "icmp", "dns", "mcp_server")

with `Annotated[Union[...], Field(discriminator="type")]` on the parent
union (MonitorAuthConfig and CheckTypeDetailsDto). Pydantic's
discriminator-aware union resolution now picks the right subtype in O(1)
on validation, vs the previous "try every member, keep the first that
parses" fallback that misclassified shape-equivalent subtypes (e.g.
BearerAuthConfig vs BasicAuthConfig — both `{vault_secret_id}` only).

Spec refresh also propagates the regular field-level fixes from the
upstream typing audit. ruff, mypy strict, and pytest (681 tests) pass.

Made-with: Cursor

Author: caballeto