Docs: Cookbook section with real-world recipes

[yuriizee]

Motivation

The docs cover every feature in isolation, but newcomers ask "how do I wire this into my actual app". A Cookbook section with copy-paste recipes would close that gap — and each recipe is a small, self-contained docs PR, perfect for a first contribution.

Recipe ideas (one PR per recipe is ideal)

• API resource responses: DTO → toResponse() with #[Hidden] internals
• Importing a large CSV with lazyCollection() (flat memory profile)
• Form request → fromRequest() with #[Rules] + #[Pipe] sanitization
• Nested DTO graphs: order → items → product with #[DataCollection]
• Storing encrypted PII with EncryptedCast
• Consuming a third-party API: #[MapPropertyName] + #[TransformKeys] for snake_case payloads
• Deploy checklist: MetadataRegistry::setStoragePath() + vendor/bin/sdo-warm

Where to look

Docs live in docs/ (VitePress). npm install && npm run docs:dev gives a live-reload server. Add the section to the sidebar in docs/.vitepress/config.*.