Add JSON-LD structured data for recipes

- Create recipeJsonLd.ts function with Schema.org compliant Recipe markup
- Add API endpoint at /api/rezepte/json-ld/[name] for on-demand generation
- Include proper ISO 8601 time parsing for German formats
- Add rel="alternate" link in recipe pages for discoverability
- Set author to Alexander Bocken with proper Person type
- Include caching headers for performance optimization

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/routes/api/rezepte/json-ld/[name]/+server.ts

@@ -0,0 +1,32 @@
+import { json, type RequestHandler } from '@sveltejs/kit';
+import { Recipe } from '../../../../../models/Recipe';
+import { dbConnect, dbDisconnect } from '../../../../../utils/db';
+import { generateRecipeJsonLd } from '$lib/js/recipeJsonLd';
+import type { RecipeModelType } from '../../../../../types/types';
+import { error } from '@sveltejs/kit';
+
+export const GET: RequestHandler = async ({ params, setHeaders }) => {
+  await dbConnect();
+  let recipe = (await Recipe.findOne({ short_name: params.name }).lean()) as RecipeModelType;
+  await dbDisconnect();
+
+  recipe = JSON.parse(JSON.stringify(recipe));
+  if (recipe == null) {
+    throw error(404, "Recipe not found");
+  }
+
+  const jsonLd = generateRecipeJsonLd(recipe);
+
+  // Set appropriate headers for JSON-LD
+  setHeaders({
+    'Content-Type': 'application/ld+json',
+    'Cache-Control': 'public, max-age=3600' // Cache for 1 hour
+  });
+
+  return new Response(JSON.stringify(jsonLd, null, 2), {
+    headers: {
+      'Content-Type': 'application/ld+json',
+      'Cache-Control': 'public, max-age=3600'
+    }
+  });
+};