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/lib/js/recipeJsonLd.ts

@@ -0,0 +1,126 @@
+function parseTimeToISO8601(timeString: string): string | undefined {
+  if (!timeString) return undefined;
+  
+  // Handle common German time formats
+  const cleanTime = timeString.toLowerCase().trim();
+  
+  // Match patterns like "30 min", "2 h", "1.5 h", "90 min"
+  const minMatch = cleanTime.match(/(\d+(?:[.,]\d+)?)\s*(?:min|minuten?)/);
+  const hourMatch = cleanTime.match(/(\d+(?:[.,]\d+)?)\s*(?:h|stunden?|std)/);
+  
+  if (minMatch) {
+    const minutes = Math.round(parseFloat(minMatch[1].replace(',', '.')));
+    return `PT${minutes}M`;
+  }
+  
+  if (hourMatch) {
+    const hours = parseFloat(hourMatch[1].replace(',', '.'));
+    if (hours % 1 === 0) {
+      return `PT${Math.round(hours)}H`;
+    } else {
+      const totalMinutes = Math.round(hours * 60);
+      return `PT${totalMinutes}M`;
+    }
+  }
+  
+  return undefined;
+}
+
+export function generateRecipeJsonLd(data: any) {
+  const jsonLd: any = {
+    "@context": "https://schema.org",
+    "@type": "Recipe",
+    "name": data.name?.replace(/<[^>]*>/g, ''), // Strip HTML tags
+    "description": data.description,
+    "author": {
+      "@type": "Person",
+      "name": "Alexander Bocken"
+    },
+    "datePublished": data.dateCreated ? new Date(data.dateCreated).toISOString() : undefined,
+    "dateModified": data.dateModified || data.updatedAt ? new Date(data.dateModified || data.updatedAt).toISOString() : undefined,
+    "recipeCategory": data.category,
+    "keywords": data.tags?.join(', '),
+    "image": {
+      "@type": "ImageObject",
+      "url": `https://bocken.org/static/rezepte/full/${data.short_name}.webp`,
+      "width": 1200,
+      "height": 800
+    },
+    "recipeIngredient": [] as string[],
+    "recipeInstructions": [] as any[],
+    "url": `https://bocken.org/rezepte/${data.short_name}`
+  };
+
+  // Add optional fields if they exist
+  if (data.portions) {
+    jsonLd.recipeYield = data.portions;
+  }
+
+  // Parse times properly for ISO 8601
+  const prepTime = parseTimeToISO8601(data.preparation);
+  if (prepTime) jsonLd.prepTime = prepTime;
+
+  const cookTime = parseTimeToISO8601(data.cooking);
+  if (cookTime) jsonLd.cookTime = cookTime;
+
+  const totalTime = parseTimeToISO8601(data.total_time);
+  if (totalTime) jsonLd.totalTime = totalTime;
+
+  // Extract ingredients
+  if (data.ingredients) {
+    for (const ingredientGroup of data.ingredients) {
+      if (ingredientGroup.list) {
+        for (const ingredient of ingredientGroup.list) {
+          if (ingredient.name) {
+            let ingredientText = ingredient.name;
+            if (ingredient.amount) {
+              ingredientText = `${ingredient.amount} ${ingredient.unit || ''} ${ingredient.name}`.trim();
+            }
+            jsonLd.recipeIngredient.push(ingredientText);
+          }
+        }
+      }
+    }
+  }
+
+  // Extract instructions
+  if (data.instructions) {
+    for (const instructionGroup of data.instructions) {
+      if (instructionGroup.steps) {
+        for (let i = 0; i < instructionGroup.steps.length; i++) {
+          jsonLd.recipeInstructions.push({
+            "@type": "HowToStep",
+            "name": `Schritt ${i + 1}`,
+            "text": instructionGroup.steps[i]
+          });
+        }
+      }
+    }
+  }
+
+  // Add baking instructions if available
+  if (data.baking?.temperature || data.baking?.length) {
+    const bakingText = [
+      data.baking.temperature ? `bei ${data.baking.temperature}` : '',
+      data.baking.length ? `für ${data.baking.length}` : '',
+      data.baking.mode || ''
+    ].filter(Boolean).join(' ');
+    
+    if (bakingText) {
+      jsonLd.recipeInstructions.push({
+        "@type": "HowToStep",
+        "name": "Backen",
+        "text": `Backen ${bakingText}`
+      });
+    }
+  }
+
+  // Clean up undefined values
+  Object.keys(jsonLd).forEach(key => {
+    if (jsonLd[key] === undefined) {
+      delete jsonLd[key];
+    }
+  });
+
+  return jsonLd;
+}