Closes-N drift 🎯

Issue #1554 — paste a PR body and see which issues GitHub would actually close on merge vs which silently stay open.

The trap

GitHub only links an issue when a close keyword immediately precedes the number. A bare comma list does not distribute the keyword:

Closes #1, #2, #3      →  closes ONLY #1   (#2, #3 stay open — silent drift)
Closes #1, closes #2   →  closes #1 AND #2  (repeat the keyword)

Keywords: close / closes / closed / fix / fixes / fixed / resolve / resolves / resolved.

Try it

GitHub will close:

Referenced but NOT closed (drift risk):

What this PR ships (#1554)

1. PR template fix — the template literally recommended the broken Closes #1, #2, #3 form. Corrected to Closes #1, closes #2 + a warning about the bare list.

2. pr-body-lint.yml — advisory (never-failing) check: if a PR title references #N but the body has no close keyword, it emits a ::warning:: nudge.

Out of scope (per the issue): heuristic auto-closing — false-closes create their own drift. The one-time sweep of ~50 stale issues is tracked separately.