519a538: Add Next.js renderer and shadcn-svelte component library.### New:
@json-render/next -- Next.js renderer that turns JSON specs into full Next.js applications with routes, layouts, SSR, metadata, data loaders, and static generation. Client and server entry points at @json-render/next and @json-render/next/server. Includes built-in Link, Slot, error boundary, loading, and not-found components.@json-render/shadcn-svelte -- Pre-built shadcn-svelte components for json-render Svelte apps. 36 components built on Svelte 5 + Tailwind CSS with state binding, validation, and action support. Server-safe catalog at @json-render/shadcn-svelte/catalog.519a538]