Release checklist line

HMAC and entropy fixtures

Required evidence

• cargo test -p uselesskey-hmac --all-features; cargo test -p uselesskey-entropy --all-features.
• Link the workflow run, artifact, or local command output in this issue.
• Update docs/release/evidence-matrix-v0.7.0.md if this line is promoted from Pending RC run to concrete evidence.

Claim boundary

This proves release readiness for a test-fixture promise. It does not prove cryptographic correctness or production key-management suitability.