Next.js App Router taste

# Next.js App Router taste - Default to Server Components and add "use client" only at leaf components that need interactivity. Confidence: 0.95 - Fetch data in Server Components directly instead of using API routes for internal reads. Confidence: 0.90 - Use Server Actions for mutations and validate input with zod. Confidence: 0.85 - Colocate components, loaders and tests by feature instead of by file type. Confidence: 0.80 - Use Tailwind CSS with a small set of design tokens in CSS variables. Confidence: 0.85 - Use next/image and next/font for all images and fonts. Confidence: 0.90 - Add loading.tsx and error.tsx to every route segment that fetches data. Confidence: 0.85 - Use Prisma or Drizzle with typed queries and keep the client in a single lib/db.ts. Confidence: 0.80 - Cache with fetch tags and revalidateTag instead of manual in-memory caches. Confidence: 0.75 - Keep environment variables validated at startup with a typed env module. Confidence: 0.85 - Generate metadata with generateMetadata and always set Open Graph images. Confidence: 0.85 - Avoid barrel files in large apps because they hurt build times. Confidence: 0.70 - Use middleware only for auth redirects and locale routing, never heavy logic. Confidence: 0.80 - Test critical flows with Playwright and components with vitest. Confidence: 0.80 - Deploy on Vercel with preview deployments for every pull request. Confidence: 0.75