feat(website): add samples/cookbook page with recipe browser

Integrates the cookbook/ folder into the website's Samples page:

Data Structure:
- Add cookbook/cookbook.yml manifest defining cookbooks and recipes
- Add .schemas/cookbook.schema.json for validation
- Add COOKBOOK_DIR constant to eng/constants.mjs

Build Integration:
- Add generateSamplesData() to generate samples.json from cookbook.yml
- Include recipe variants with file paths for each language
- Add samples count to manifest.json

Website UI:
- Create samples.ts with FuzzySearch, language/tag filtering
- Replace placeholder samples.astro with functional recipe browser
- Recipe cards with language indicators and action buttons
- Language tabs for switching between implementations
- View Recipe/View Example buttons open modal
- GitHub link for each recipe

Features:
- Search recipes by name/description
- Filter by programming language (Node.js, Python, .NET, Go)
- Filter by tags (multi-select with Choices.js)
- 5 recipes across 4 languages = 20 recipe variants

eng/constants.mjs

@@ -123,6 +123,7 @@ const PROMPTS_DIR = path.join(ROOT_FOLDER, "prompts");
 const AGENTS_DIR = path.join(ROOT_FOLDER, "agents");
 const SKILLS_DIR = path.join(ROOT_FOLDER, "skills");
 const COLLECTIONS_DIR = path.join(ROOT_FOLDER, "collections");
+const COOKBOOK_DIR = path.join(ROOT_FOLDER, "cookbook");
 const MAX_COLLECTION_ITEMS = 50;
 
 // Agent Skills validation constants
@@ -145,6 +146,7 @@ export {
   AGENTS_DIR,
   SKILLS_DIR,
   COLLECTIONS_DIR,
+  COOKBOOK_DIR,
   MAX_COLLECTION_ITEMS,
   SKILL_NAME_MIN_LENGTH,
   SKILL_NAME_MAX_LENGTH,