agent-assure flagship demo

Final visible output:
  case: shared-source-multi-claim
  baseline:  recommendation=approve; outcome=approve
  candidate: recommendation=approve; outcome=approve
  output equivalence: preserved

Process assurance:
  missing evidence link: claim-duration
  reason: MATERIAL_CLAIM_MISSING_EVIDENCE
  fixture equivalence: pass
  classification: new_failure

CI gate:
  blocked as expected

Artifacts:
  demo-summary.json
  baseline-report/evaluation-report.md
  evidence-report/evaluation-report.md
  comparison-report/comparison-report.md
  ci-report/evidence-packet.json
  evidence-diff.html

Demo result:
  success: identical output, process regression caught
