feature-sliced-design は何をしますか？
Official Feature-Sliced Design (FSD) v2.1 skill for applying the methodology to frontend projects. Use when the task involves organizing project structure with FSD layers, deciding where code belongs, placing static assets (images, icons, fonts, PDFs), grouping closely related slices, defining public APIs and import boundaries, resolving cross-imports or evaluating the @x pattern, deciding whether to create or remove an entity, evaluating whether the entities layer is needed at all, deciding whether logic should remain local or be extracted, migrating from FSD v2.0 or a non-FSD codebase, integrating FSD with frameworks (Next.js App Router and Pages Router, Nuxt, Vite, Astro), or implementing common patterns such as authentication, API handling, Redux, and TanStack Query (React Query) within FSD.