feat(signals): slop signal — generated/vendored/dependency/docs matchers

[JSONbored]

Parent roadmap: #525
Parent epic: #530

Goal

Implement path-matcher signals: generated/vendored/lockfile/min edits, dependency-bump-only, docs-only padding.

Reuse

New pure path matchers (sibling to isTestFile).

Acceptance

Each matcher classifies representative paths correctly.

Testing

npm run test:ci, 97%+ coverage. Public/private output boundary preserved; deterministic where applicable.