Preserve experiment artifact hashes with offline verifier and CI

[Daniele-Cangi]

Changes

• Add a dependency-free manifest creator and verifier for local lab artifacts. The status field is explicitly analyst supplied.
• Add synthetic unit tests for hashing, post-recording mutation, missing/outside paths, duplicate records and version checks.
• Add first CI workflow on master that tests this standalone artifact contract without executing Scapy or network probes.
• Document scope, exact invocation, and why hashes alone do not prove attribution or chain of custody.

Validation

GitHub Actions must pass offline tests before merge. No existing measurement scripts or historical experiment records were changed.