refactor: convert repository to monorepo - #7

What changed

• moved the existing Next.js website into apps/www without changing its application source
• added pnpm workspace and Turborepo configuration at the repository root
• moved shared formatting, linting, and Lefthook orchestration to the monorepo root
• added app-local Vercel configuration for the apps/www project root
• updated ignore patterns and the lockfile for workspace-aware paths

Why

The CLI package should be reviewed independently from the repository-layout migration. This PR establishes the monorepo foundation so package work can land as a focused stacked PR.

Impact

The website remains the only workspace in this layer and continues to use the existing shadcn registry builder and existing StyleX setup. Root commands now delegate through Turbo to apps/www.

Validation

• pnpm install --frozen-lockfile
• pnpm run check
• pnpm run typecheck
• current main CI build is green with the unchanged application build configuration