refactor: Improve error handling in PowerDNSAPIClient and streamline response processing
fix: Update RecordController to directly return records without unnecessary mapping
refactor: Update DomainRepository and RecordRepository to remove nullable types for IDs
fix: Change User domains fetch strategy to lazy loading for performance improvement
fix: Enhance user authentication handling in UserFilter to ensure authenticated user presence
refactor: Improve DomainService to enforce ownership checks before domain deletion
refactor: Update RecordService to streamline record retrieval and ensure proper domain association
test: Add OpenAPI generation test to validate API documentation endpoint
test: Implement PowerDNSAPIClient tests to verify HTTP method usage and error handling
test: Create DomainService tests to validate domain ownership and deletion logic
test: Add application-test.properties for in-memory database configuration during tests