v0.13.0

Changed

• Releases now sign with the modern Sigstore bundle. The release's checksums.txt is
  signed with keyless cosign into a single checksums.txt.sigstore.json bundle (via
  cosign-installer v4), replacing the separate checksums.txt.sig + .pem files. Verify with
  cosign verify-blob --bundle checksums.txt.sigstore.json --certificate-identity-regexp … ….
  The self-scan, the GitHub Action, and the docs verify the new bundle; the install/quickstart
  recipes are updated accordingly.

Added

• draugr tools install now verifies upstream cosign signatures (where the upstream
  publishes them), on top of the mandatory SHA-256 pin. For Trivy, Draugr verifies the keyless
  signature over the release's checksums file — checking the signing certificate identity and
  OIDC issuer via the cosign CLI, then confirming the downloaded archive is listed in the
  signed checksums — giving signed provenance, not just integrity. It degrades gracefully to
  SHA-256-only (with a note) when cosign isn't installed or the upstream isn't signed (e.g.
  gitleaks); if cosign is present but verification fails, the install aborts. Each installed
  tool reports what was verified.