test(loop-init): cover every scaffold combination

[shixi-li]

Summary

Exercise every supported loop-init pattern × tool combination in a fresh
temporary directory.

Problem

loop-init supports seven patterns and four tools, but the test suite sampled
only a handful of those 28 combinations. The manual validation checklist also
listed only two patterns, while STATE.md explicitly calls for fresh-project
validation across all patterns.

Changes

• Add a table-driven 28-combination scaffold matrix to the existing CLI test
  process.
• Verify state, observability, constraints, the selected tool's primary skill,
  and tool-specific configuration.
• Verify circuit-breaker assets and ledger contents for fix-capable patterns,
  plus their absence from report-only patterns.
• Verify intake assets are present only for Issue Triage.
• Expand the manual validation checklist to all 28 rows and distinguish its UX
  checks from the automated contract.

Test design

The matrix stays in the existing CLI test file because the suite's
bundle-assets concurrency test replaces shared bundled assets. Running a
second test file in parallel exposed a transient missing-template failure; a
single process preserves the existing serialized contract without retries.

Testing

• cd tools/loop-init && npm test — 53/53 passed
  • 25 existing CLI tests
  • 28 pattern × tool scaffold cases
• bash scripts/ci-validate-gates.sh
  • full registry and tool suite passed
  • all 53 loop-init tests passed in the official sibling-dependency setup
• bash scripts/ci-audit-gates.sh
  • reference score 100
  • every starter passed the L1 gate
• git diff --check

Scope

This PR changes tests and validation documentation only. It does not change
scaffold output, package dependencies, or runtime behavior.

[github-actions]

Thanks @shixi-li for contributing a docs improvement — visible, reviewable PRs like this grow the reference for everyone.

What happens next

• Maintainer aims for same-day review on story, adopter, and scoped docs/example PRs (CONTRIBUTING.md).
• good first issue PRs: comment on the linked issue so we can assign and close on merge.

More ways to help

• Contributor quickstart + open issues
• Good first issue backlog

— loop-engineering maintainers