feat(landing): implement enums, models, and dtos for landing service
This MR introduces the core domain components for the Landing Page microservice, including Enums, JPA Entities, and DTOs. These changes provide the foundation for properties preview, platform statistics, FAQs, and waitlist management.
Key Changes:
- Enums: Defined PropertyStatus, PropertyType, and FAQCategory.
- Models: Implemented Property, FAQ, WaitlistEntry, PlatformStat, and Feature entities with JPA auditing (AbstractAuditingEntity).
- DTOs: Created a complete data transfer layer including LandingPageDataDTO for aggregate responses and WaitlistRequestDTO with validation.
- Standards: Adhered to existing workspace architecture (UUID-based IDs, Lombok, and JSR-303 validation).