bug_report.yml's 'Which file?' dropdown has no audit.yaml option

[yakew7]

Where: .github/ISSUE_TEMPLATE/bug_report.yml:27-36 ("Which file?" dropdown):

- type: dropdown
  id: script
  attributes:
    label: Which file?
    options:
      - unfair.py
      - fair.py
      - Jupyter notebook
      - Other

The gap: audit.yaml is a real, first-class per-audit file now - README.md describes it as "the declarative manifest read by the benchmark harness," and .github/workflows/audits.yml's benchmark-harness job runs directly against it - but it has no dedicated option in this dropdown. A bug reporter hitting an audit.yaml problem (a bad dataset path, a malformed column mapping) has to pick the catch-all "Other" instead of a specific option, unlike every other audit file type.

Why it matters: minor, but it's the same class of "template hasn't kept up with what the project actually ships" drift as other closed issues in this repo (e.g. bug_report.yml's audit-domain dropdown missing two domains, closed via #314) - audit.yaml didn't exist as a concept when this dropdown was first written and the template was never revisited.

Suggested fix: add audit.yaml as a dropdown option, alongside unfair.py, fair.py, and Jupyter notebook.