Verifying release artifacts

Every GitHub Release tarball ships with four supply-chain artifacts:

• *.sha256 — a plain checksum, no tooling required (shasum -a 256 -c <file>.sha256).
• *.cdx.json — a CycloneDX SBOM of the build's dependency graph.
• *.sig + *.pem — a cosign keyless signature and its Fulcio certificate, for offline verification.
• a SLSA build provenance attestation recorded in GitHub, binding the tarball's digest to the workflow run that produced it.

Verify provenance (proves it was built by this repo's release workflow):

gh attestation verify vllm-vcr-vllm0.23-x86_64-unknown-linux-musl.tar.gz \
  --repo neuralmagic/vllm-vcr

Verify the cosign signature without GitHub:

cosign verify-blob \
  --certificate vllm-vcr-vllm0.23-x86_64-unknown-linux-musl.tar.gz.pem \
  --signature  vllm-vcr-vllm0.23-x86_64-unknown-linux-musl.tar.gz.sig \
  --certificate-identity-regexp '^https://github.com/neuralmagic/vllm-vcr/' \
  --certificate-oidc-issuer https://token.actions.githubusercontent.com \
  vllm-vcr-vllm0.23-x86_64-unknown-linux-musl.tar.gz