feat(kyc): add review workflow and liveness webhook support (V2)

Summary This MR introduces the next KYC backend increment (V2) by adding a complete review workflow and liveness flow integration while keeping existing APIs backward-compatible.

What was added

1) Review workflow

• Investor endpoint to submit a KYC dossier for review with required confirmations.
• Admin endpoint to submit review decisions with checklist payload.
• Admin endpoint to retrieve review details by kycId.
• Transactional finalization of review data (status/reviewer/reviewedAt consistency).

2) Liveness workflow

• Investor endpoint to start liveness for a KYC dossier.
• Webhook endpoint to apply provider callbacks:
  • POST /api/v1/webhooks/kyc/liveness/{provider}
• Basic idempotence guard to safely handle duplicate callbacks.
• Validation to reject provider/session inconsistencies.

3) Persistence and service layer

• Added repositories:
  • KycReviewRepository
  • LivenessCheckRepository
• Added service contracts and implementations:
  • KycReviewService, KycReviewServiceImpl
  • KycLivenessService, KycLivenessServiceImpl

4) Tests

• Added unit tests for core business logic:
  • KycReviewServiceImplTest
  • KycLivenessServiceImplTest
• Updated controller web-slice test wiring to include newly introduced services.

5) Documentation

• Updated CHANGELOG.md with the new V2 scope and validation scenarios.

Validation

• Local build and test run completed successfully (mvn test).
• Manual API scenarios can be executed in Postman for:
  • review submission
  • review decision
  • liveness start
  • webhook callback + duplicate callback behavior

Backward compatibility

• Existing endpoints remain unchanged.
• New capabilities are additive (non-breaking).