Close the reproducible v0.5.0 DepMap workflow

[rsolerortuno]

Closes #62.

Summary

• introduces the reproducible v0.5.0 DepMap release-closure runner;
• separates module release readiness from candidate activation;
• distinguishes fixture and real evidence classifications;
• validates local paths, manifests, checksums and artifact identities;
• prevents fixture evidence from being represented as real evidence;
• verifies baseline preservation;
• compares both stage outputs and top-level scientific release artifacts;
• sanitizes malformed-manifest failures;
• rejects URLs, escaping relative paths and credential-bearing content;
• retains controlled fixture failure states;
• adds direct failure-path and isolation tests;
• performs no automatic tag, release or production activation.

Fixture result

The synthetic fixture is intentionally blocked as:

blocked_fixture_evidence

This PR validates the architecture and does not claim a completed real DepMap
melanoma analysis.

Validation

• Claude: APPROVE
• AGY advisory audit: COMPLETED
• focused tests: passed
• full tests: passed
• pipeline validation: passed
• final test exit code: 0
• final process exit code: 0