fix(reviewer-bot): repair stale labels after projection changes

[PLeVasseur]

Summary

• add a one-time status_projection_epoch migration so projection-logic changes can relabel already-repaired PRs like [Coding Guideline]: Do Not Depend on Function Pointer Identity #256 even when no new touched-item mutation occurs
• build the repair set from open reviewer-bot status labels plus tracked active reviews, and only advance the projection epoch after label sync succeeds
• add schedule-path regression coverage for the repair sweep, epoch advancement, and the pre-repaired PR case

Testing

• uv run pytest .github/reviewer-bot-tests/test_main.py .github/reviewer-bot-tests/test_reviewer_bot.py
• uv run ruff check --fix

[netlify]

✅ Deploy Preview for scrc-coding-guidelines ready!

Name	Link
🔨 Latest commit	faad422
🔍 Latest deploy log	https://app.netlify.com/projects/scrc-coding-guidelines/deploys/69c598a852adcb00088c692d
😎 Deploy Preview	https://deploy-preview-543--scrc-coding-guidelines.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.