Add persistent memory integrity evidence gates

[bozicovichsantiago20-oss]

Summary

• adds AG04 persistent memory integrity evidence checks for write authorization, provenance/trust labels, retrieval boundaries, tamper evidence, poisoning detection, and quarantine/removal
• adds an assessment-process memory evidence table before rating AG04
• extends report output fields with memory write sources, trust controls, remediation controls, and residual cache risk

Validation

• git diff --check
• Markdown fence balance check
• Required marker check for Memory Integrity Evidence Checklist, AG04 Memory Integrity Gate, memory output fields, and residual cache risk

Bounty target: review issue + Improver Moderate for #1374 if accepted. Payment details can be provided privately after maintainer acceptance.