Add full-stack Cloudflare and Vercel recipes to docs

[JoviDeCroock]

Summary

• Adds a Full-Stack Cloudflare recipe covering D1 (SQLite), KV caching, wrangler config, migrations, typed bindings, and parameterized queries in loaders/API routes
• Adds a Full-Stack Vercel recipe covering Vercel Postgres (Neon), KV (Upstash Redis), environment provisioning, and deployment
• Registers both recipes in the sidebar nav and route manifest
• Updates prev/next navigation links on adjacent docs (Testing, Migrate from Next.js)

Test plan

• Verify docs site builds successfully
• Check both new recipes render at /docs/recipes/fullstack-cloudflare and /docs/recipes/fullstack-vercel
• Confirm sidebar shows both new entries under Recipes
• Verify prev/next navigation works across Testing → Cloudflare → Vercel → Migrate from Next.js

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