Agent Skills: refactor:nestjs

Refactor NestJS/TypeScript code to improve maintainability, readability, and adherence to best practices. Identifies and fixes circular dependencies, god object services, fat controllers with business logic, deep nesting, and SRP violations. Applies NestJS patterns including proper module organization, provider scopes, custom decorators, guards, interceptors, pipes, DTOs with class-validator, exception filters, CQRS, repository pattern, and event-driven architecture. Transforms code into exemplary implementations following SOLID principles.