Surface content drift in code anchor audits

[divo12]

Summary

• print content-drifted claims in greplica graph audit anchors
• return exit status 1 when content drift is present, even when every anchor still resolves
• add an end-to-end CLI regression that seeds a baseline fingerprint, changes real code from 3 to 8, and verifies structural audit sections remain clean

Why

The anchor audit already computes drifted[], but the CLI neither displayed those results nor counted them as audit failures. A claim could therefore point to changed code while the command appeared successful to a developer or CI job.

After this change, content drift is visible alongside structural anchor failures:

Content drift:
- claim.foo -> mod.py#foo

This PR only surfaces detection. It does not modify, demote, or supersede memory.

Verification

• ECC pre-push typecheck, full test, offline browser regression, and build passed
• node scripts/check-anchor-drift.js passed
• existing anchor-drift-supersede eval passed: both stale claims were superseded and no fresh claims were changed