fix(eval): reject empty task slugs

[jdchawla29]

Summary

• require explicit task slugs to contain at least one character
• add coverage for rejecting slug=""

Why

The SDK reports Task.slug directly to trace and rollout endpoints.

Impact

Default slug generation is unchanged. Explicit empty slugs now fail immediately during Task construction with the same Pydantic validation used for empty environment names and task IDs.

Validation

• uv run '--with=.[dev]' pytest hud/eval/tests/test_task.py (18 passed)
• uv run '--with=.[dev]' ruff check hud/eval/task.py hud/eval/tests/test_task.py
• uv run '--with=.[dev]' pyright hud/eval/task.py

---

Note

^{Cursor Bugbot is generating a summary for commit a1a7717. Configure here.}

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: a1a7717f83

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".