dunn.dev/pipeline 4.0.0

Breaking major (dead-surface removal + supply-chain hardening).

Removed (zero-consumer, estate-wide verified):
- cloudflare-pages component + recipes/validate slots (use cloudflare-worker)
- release-create `extra_sbom_jobs` input + upload-extra-sbom job/recipe

Supply chain:
- ci image bakes osv-scanner + cosign (checksum-verified) → osv-verdict
  gate and node-publish signing install nothing at runtime
- syft installer pinned to a release tag (was mutable main)
- template tool-version defaults are Renovate-tracked (customManager)

Lint: lint-includes (supersedes lint-suppression) — structural YAML
bijection + suppression coverage. cosign/syft fallback defaults aligned
to baked versions; go-sbom skips .sha256 sidecars.

Merged via !96 (rebased onto current main; pipeline green incl. osv-verdict).