chore: add notable PostgreSQL bug fixes

[github-actions]

Automated PostgreSQL release-notes scout.

tools/scrape_release_notes.py fetched the latest ~2 minor
release notes per major in {15,16,17,18}, filtered the
<li class="listitem"> entries by severity keywords, deduped
against data/known_bugs.json, and surfaced the top 5 per
major for review. The candidates are in proposed-bugs.json.

Action items for a human:

• Decide which entries earn a permanent seat. The list
  is biased toward data-integrity / crash / replication
  bugs; doc-only or trivial entries should be dropped.
• Rename curator IDs if needed (e.g. PG17-a1b2c3d4e
  → PG17-MERGE-RACE-CONDITION-01) before merging.
• Merge selected entries into data/known_bugs.json:
  bash uv run python tools/scrape_release_notes.py --write --yes uv run python tools/generate_cve_sql.py git add data/known_bugs.json pgFirstAid.sql view_pgFirstAid.sql view_pgFirstAid_managed.sql git commit -m "chore: refresh known-bugs catalog"
• Delete proposed-bugs.json before merge.

Notes on the keyword filter (HIGH/MEDIUM lists live in
tools/scrape_release_notes.py): the curated list is small,
intent is curated quality over recall, and silent false
negatives are preferred over noisy false positives. Tune the
keyword lists if the proposals get noisy or thin.