Cleanup: strip pre-existing ephemeral issue/PR refs from code comments (repo-wide) #414

Follow-up to the Durable-References guidance in AGENTS.md (the rule that originated in this repo and was ported to playbook #281 and patterns #384 — both of which have their own tracked cleanup issue; this one was missing).

New PRs' comments were cleaned during review, but the rule isn't applied retroactively: ~90 pre-existing bare #NNN issue/PR references remain in code comments across acq, acq.backends/*.sh, scripts/*.sh, and test/bats/*.bats (e.g. acq.backends/msb.sh:492 "PR #302 review", acq.backends/progress.sh:8 and :41 "issue #287").

Scope

Repo-wide sweep of shell-script + bats-test comments to rewrite bare #NNN into self-contained prose, citing an ADR (docs/adr/) where a design decision applies.

Keep (out of scope)

• Commit messages, CHANGELOG, PR bodies, ADR Links sections, Version-History rows — ephemeral contexts where refs are allowed.
• Any NIST/control-mapping-style tag (none expected in this repo, but consistent with the playbook/patterns carve-out).
• Test names encoding a stable regression identifier.

Approach

One comments-only PR, ./scripts/test-acq-bats + shellcheck green throughout. Consider a CI grep-guard to prevent regression, mirroring whatever playbook/patterns land in #281/#384.

AI-assisted (OpenCode). Found during backlog grooming — this repo originated the Durable-References rule but was the only one of the three missing its own cleanup issue.