[FIX] Reviews tab: GitHub-approved PRs leave open work

[haimbj1]

Why

A PR approved on GitHub kept sitting under "open work". Two causes:

1. GitHub removes the review request the moment a review is submitted, so the approved PR vanishes from the collector's review-requested: search — the approval was never collected. The row survived only via its offline review file, which carries no GitHub state.
2. my_review took the single most recent review event. A later thread reply lands as a COMMENTED review and masked a standing approval.

What

• New reviewed-by:<login> search in collect.sh writes my_reviews.json (url → my effective review state) for open PRs I already reviewed; best-effort, a failed fetch keeps the previous file.
• my_review is now the effective state: the newest APPROVED / CHANGES_REQUESTED wins over trailing COMMENTED events (last:10 instead of last:1).
• build.py ships the map as DATA.my_reviews; the page seeds GH_MY_REVIEW from it, so the existing decided logic and the "✓ approved on GitHub" pill now cover rows with no live request too.

Verified: shellcheck, py_compile, CI script-extraction + node --check, jq fixtures for the effective-state expression (approve-then-comment stays APPROVED), and the live reviewed-by query returns the expected APPROVED map.