chore(guardrails): reinstall the commit-msg git hooks on operator machines after the convention move #9735

Parent

Refs #5906

Depends on

• refactor(source-control): read the commit and PR convention keys from docs/conventions/source-control.yaml #9725
• refactor(guardrails): resolve the commit convention from docs/conventions/source-control.yaml #9727

Needs a person: the installed commit-msg hooks live in each operator machine's clones and user git config, which no CI agent can reach.

Outcome

Every operator machine runs the guardrails commit-msg hook from a release whose resolver reads
docs/conventions/source-control.yaml, so this repository's .claude/source-control.md can be deleted.

Decisions

• Migrate per-skill .claude config files to userConfig, one conventions doc, or the cascade (ADR 0018) #5906 (comment 2026-10-04): keep .claude/source-control.md with identical keys until a release carrying the
  new reader has shipped and the git hooks have been reinstalled.

Done when

• A guardrails release containing the change that closed the guardrails resolver slice is published (git tag --contains <its merge commit> prints a guardrails tag).
• On each operator machine, /guardrails:setup apply install-commit-msg (or the config-hook lane, where installed) has been re-run, and a commit in this repository with a non-conforming subject is refused.
• A comment on this issue lists the machines done.