feat(kyc): enforce admin query validation and standardize constraint error handling
- Add strict request-param validation on admin KYC endpoints (@Validated, @Min/@Max, @NotBlank)
- Introduce dedicated ConstraintViolationException handling with INVALID_QUERY_PARAM contract
- Disable spring.jpa.open-in-view for production safety
- Keep behavior backward compatible except invalid params now fail fast with explicit 400 payloads