- Add auth_test.go with setupTestDB/setupAuthService helpers using SQLite in-memory database and GORM AutoMigrate
- Add TestAuthService_Register with duplicate username/email validation and invalid role handling
- Add TestAuthService_Login with invalid username/password checks and inactive user validation
- Add TestJWTService_GenerateToken with database session verification and token storage validation
- Add TestJWTService_ValidateToken with invalid