Move test infrastructure (validate.bats, new-skill.bats) from scripts/ to
tests/ — the spec defines scripts/ as executable code agents can run, so
test files don't belong there. Add tests/README.md placeholders with
bats-support dependency declaration.
Update skill-audit to permit tests/ and flag other unlisted directories,
add scripts/ purpose check, and add /skill-improve near-miss exclusion.
Update skill-improve and skill-write to cover tests/ in directory lists,
scaffold template, and authoring guidance.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>