Fix GET /auth/login missing 400 in OpenAPI spec and use status constant

[ColtenOuO]

The /auth/login endpoint raises HTTP 400 when the next redirect URL is invalid or unsafe, but this response code was missing from the responses decorator — so the generated OpenAPI spec didn't document it.

Changes:

• Add HTTP_400_BAD_REQUEST to create_openapi_http_exception_doc for the login endpoint
• Replace raw integer 400 with status.HTTP_400_BAD_REQUEST for consistency with the rest of the codebase

[ColtenOuO]

Celery integration test failed without producing any test output — appears to be a runner infrastructure issue unrelated to this PR.

[vincbeck]

Celery integration test failed without producing any test output — appears to be a runner infrastructure issue unrelated to this PR.

Still, some front-end artifacts are generated from openapi specs, please run prek to fix the static check failures

[ColtenOuO]

I have run prek to fix static check failures.

The test uses cmd_timeout=0.001 (1ms) to verify timeout behavior, but on a loaded CI runner, paramiko raises SSHException: Timeout opening channel before the channel is even established — a different exception type than expected. This is a pre-existing flaky test tracked in #65864.

I think the new failure is unrelated to this PR (?

[vincbeck]

I have run prek to fix static check failures.

The test uses cmd_timeout=0.001 (1ms) to verify timeout behavior, but on a loaded CI runner, paramiko raises SSHException: Timeout opening channel before the channel is even established — a different exception type than expected. This is a pre-existing flaky test tracked in #65864.

I think the new failure is unrelated to this PR (?

You are correct