chore: make commitlint low-friction

[kiro-systemf]

Applies the org-decided low-friction commitlint policy to repo-root commitlint.config.ts (commitlint change only).

Why

Cosmetic rules at error level fail whole agent commits for no downstream benefit:

• Trailing-period failures: subject/header/body-full-stop hard-failed any commit ending in ..
• Unguessable-scope failures: scope-enum rejected scopes an agent cannot reliably guess.
• type-matches-diff-shape: a heuristic that inspected the staged diff and hard-failed when the chosen type did not match a path-shape guess — non-deterministic across amend/rebase, protects nothing.

Releases here run on changesets (.changeset/*.md), not commit messages, so scope / punctuation / type-vs-diff have zero release impact.

Changes

• subject/header/body-full-stop → 0 (off).
• scope-enum → 0; deleted the static SCOPES enum.
• scope-case → 1 (warn, kebab-case nudge).
• Deleted type-matches-diff-shape and all its machinery (stagedFiles(), ALLOWED_BY_SHAPE, isDoc/isTest/isCI/isLockfile/isTooling/matchesAny, execFileSync / node:child_process import).
• body-leading-blank / footer-leading-blank → 1 (warn).
• Kept at error: no-ai-coauthors, type-empty, type-case lower-case, type-enum (existing list verbatim), subject-empty.

Verified

printf 'feat: add thing.' | pnpm exec commitlint exits 0; an unguessable scope exits 0; a bad type still fails; --print-config json loads.

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