diffcone 0.3.0

CI

• diffcone report --dir DIR reports on many CI runs of the actions: per
  job, the share pull requests selected and why some were planned from the
  code, and for pushes whether each was checked, its new failures, flaky
  re-runs and misses. It exits 1 on a miss or a check that failed.
• A new report action runs it on a schedule over the recent runs'
  artifacts, comments the report on an issue, and opens an issue for each
  miss.
• run and record write context.json (what they did, and why a plan
  was made from the code or a push was not checked) into the results they
  upload; run also writes ran.json, the plan that ran.
• The verdict record keeps for a re-run of the same commit
  (.diffcone/check.json) also says whether the push was checked and
  whether the check itself failed, so a re-run reports a failed check as
  one rather than as a miss.

Execution evidence

• On Windows, uv python list run through the path shutil.which gives
  (...\uv.EXE) is recognised as an inert query, as it is elsewhere; it
  made a third of a Windows suite always selected.