Revisit ADR-0008: should .claude/rules/pr-body-contract.md stay always-loaded?

[kyle-sexton]

ADR-0008 distributes .claude/rules/pr-body-contract.md as an always-loaded rule to every gate caller so that plugin-less sessions see the PR-body contract before a bare gh pr create. The stated driver was first PRs failing the required pr-issue-linkage check.

That driver has changed: the rule itself now says a missing closing keyword or section does not fail ci-status; pr-contract leaves an advisory comment and the needs-issue-linkage label. The only gating parts are the Conventional Commits title and the do-not-merge label.

Cost: ~190 words loaded into every session in every gate-caller repo, relevant only when opening a PR. In melodic-software/.github the content is already covered at PR time by .github/PULL_REQUEST_TEMPLATE.md (closing line + four sections), .claude/source-control.md (pr_body_required_sections), and a CLAUDE.md pointer.

Options:

1. Keep always-loaded, trim to the gating facts plus one line pointing at the template.
2. Sync to an on-demand path (e.g. .claude/pr-body-contract.md) and rely on each consumer's CLAUDE.md pointer; lockstep-drift.mjs would follow the new path.
3. Keep as is, and record in ADR-0008 why the advisory switch does not change the decision.

Found by a progressive-disclosure audit in the melodic-software/.github hygiene sweep (melodic-software/.github#153).