test: cover adversarial workflow sequences

[rlippmann]

What changed

• Add a shared mixed step/apply workflow covering conflict, removal, and retry.
• Add a shared workflow that explicitly applies repairs returned by a semantic error.
• Extend the Python workflow runner with the narrow apply_repair operation.

Why

• Protect the Python 0.9 portable contract across stateful operation sequences and advisory repair handling.

Checklist

• pre-commit run (uv run pre-commit run --all-files)
• tests pass (uv run pytest)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (22c74bd) to head (dbe804e).

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #270   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            6         6           
  Lines          783       783           
=========================================
  Hits           783       783           

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.