Validate Enterprise Lab decision replay contract fixtures

[RicheyWorks]

Summary

• Adds a test-only typed reader for the Enterprise Lab decision replay / what-if contract fixtures from PR Add Enterprise Lab decision replay contract fixtures #181.
• Parses the snapshot, request, and result fixtures into nested Java records using the existing Jackson ObjectMapper tooling.
• Validates deterministic versions, IDs, timestamp, source linkage, selected backend consistency, changed/unchanged factor presence, and explicit lab-only/not-production-proof boundaries.

Test-only reader/validator added

• EnterpriseLabDecisionReplayContractReaderTest loads:
  • sample-decision-snapshot.json
  • sample-what-if-request.json
  • sample-what-if-result.json
• The reader/validator is nested inside the test class only and is not wired into Spring or any production package.

What is intentionally not implemented

• No live replay endpoint.
• No what-if endpoint.
• No runtime replay execution.
• No scoring mutation, strategy retuning, proxy behavior change, or backend mutation.
• No external storage, telemetry, analytics, export generation, release, registry publication, signing, live cloud validation, private-network validation, or GitHub settings mutation.

Safety boundaries

• Production source remains unchanged.
• The test asserts no /api/routing/replay, /api/routing/what-if, or /api/routing/decision-replay endpoint is exposed from src/main.
• The test asserts no replay/what-if controller or service wiring is present in src/main.
• The typed reader test imports no routing/scoring runtime paths.
• Replay and what-if execution remain planned/not implemented.

Tests run

• mvn -q -Dtest=EnterpriseLabDecisionReplayContractReaderTest test
• mvn -q -Dtest=EnterpriseLabDecisionReplayContractFixtureTest,EnterpriseLabDecisionReplayWhatIfPlanDocumentationTest,ReviewerTrustMapDocumentationTest test
• mvn -q test
• mvn -q -DskipTests package
• mvn -B package
• git diff --check
• git diff --cached --check
• scripts/smoke/enterprise-lab-workflow.ps1 -Package

Not-proven limits

• This does not prove executable replay or what-if behavior.
• This does not prove production traffic replay, live cloud behavior, real tenant behavior, SLA/SLO achievement, production certification, registry publication, container signing, or governance-applied status.
• This does not validate live private-network traffic or mutate real backend state.