fix(control): check native completion before restarting a parent

[osolmaz]

Summary

A parent Job can restart after Harbor has finished if the control service reads an older Bucket listing. This change checks the native result directly just before starting a parent. It avoids an unnecessary restart without changing how Harbor runs or resumes trials.

Related issue: #239.

What Changed

The control service now checks job/result.json with a fresh read after it decides that no parent is live, and before it calls the HF Jobs start API. A native finished_at stops the launch. A missing or unfinished result keeps the existing resume path.

• Added an optional fresh-read argument to the shared JSON reader, using the ObjectStore's existing cache-bypass option.
• Added regression tests for an older Bucket listing and an older cached aggregate result.
• Checked the pinned Harbor source at dcd0a7ac74b7bd417780d9cb27cd819c7ec82e4e: src/harbor/job.py (Job.run()) and src/harbor/models/job/result.py (JobResult.finished_at). Harbor still writes and owns the result and trial resume. No new record, schema, API value, UI value, or trial scheduler was added.

Testing

The stale-listing test failed before the fix and passed after it. The local unit and browser tests passed with en_US.UTF-8 for the existing USD formatting assertions.

• npm test -- --reporter=dot: 1,719 passed.
• npm run test:e2e: 77 passed on an isolated local port.
• npm run typecheck, npm run build, npm run format:check, npm run lint, npm run check:generated, npm audit --audit-level=low, and python3 scripts/check_public_privacy.py .: passed.
• No paid inference run or hosted deployment was used to test this change.

Risks

Each pending parent launch makes one extra fresh Bucket read. A missing result still allows launch; other read errors stop that reconciliation pass rather than starting a parent on uncertain evidence. This closes the observed stale-listing window, but a result that arrives after the final fresh read can still race with a launch. The hosted control service has not been changed by this PR.