feat(kyc): implement missing DAO/STD capabilities and add full Postman test suite

Implemented a new KYC iteration to cover missing DAO/STD functionalities across investor, admin, and webhook flows while preserving backward compatibility.

What was added KYC synchronization module (repository/service/endpoints) with externalId lookup support. KYC status query endpoint with timeline, recommendations, risk/completion insights. Document feature completion: get by type, count, delete by id, delete by KYC. Admin feature completion: expire KYC and delete KYC by user. Webhook integration improvement: sync-aware externalId resolution + legacy fallback.

Testing Added one consolidated Postman collection covering all microservice methods. Added one local Postman environment with ready-to-run variables. Included webhook HMAC signing flow in Postman scripts for secure callback validation.

Impact Closes major DAO/STD functional gaps. Improves operability and regression safety with complete API-level test coverage.