Evaluation: Redirect dataset uploads

[AkhileshNegi]

Is your feature request related to a problem?
Dataset uploads are currently directed to the /api/v1/evaluations/datasets endpoint, which needs langfuse credentials to upload

Describe the solution you'd like

• Redirect app/api/evaluations/datasets/route.ts to POST /api/v2/evaluations/datasets
• Maintain the multipart structure: file, dataset_name, description, duplication_factor (1–5)

Parent: #265

[kaapi-agent-bot]

Thanks for filing this — after reviewing the code, I'm not able to implement this one under the current automated-fix guardrails.

This issue asks to redirect app/api/evaluations/datasets/route.ts from POST /api/v1/evaluations/datasets to POST /api/v2/evaluations/datasets, and to adjust CreateDatasetForm validation/copy accordingly. The route change is a backend API-call/integration change (not a UI/styling change), and the automated fix workflow for this repo is scoped to UI/styling-only changes — it explicitly excludes changes to business logic, API calls, or auth. Since I can't verify here whether the /api/v2/evaluations/datasets endpoint already exists on the backend, what its request/response contract looks like, or how errors differ from v1 (all of which are needed to safely swap the endpoint and update the duplicationFactor validation/copy), this needs a human to confirm the v2 contract and make the API-call change.

Flagging for human follow-up rather than making a partial/unsafe change.