feat(seo): implement AI SEO and structured data schema

- Add robust JSON-LD schema generators (LocalBusiness, FAQ, Service, Event)
- Refactor JsonLd component to use @graph pattern for merging global/local schemas
- Create FaqBlock component with automatic FAQPage schema injection
- Inject specific JSON-LD schemas into mdx pages (home, kompetenzen, messen)
- Add structured AI SEO content (hard facts, stats, clear definitions)

components/blocks/FaqBlock.tsx

@@ -0,0 +1,64 @@
+import React from 'react';
+import { getFAQSchema } from '@/lib/schema';
+import JsonLd from '@/components/JsonLd';
+
+export interface FAQItem {
+  question: string;
+  answer: string;
+}
+
+interface FaqBlockProps {
+  title?: string;
+  subtitle?: string;
+  questions: FAQItem[];
+}
+
+export const FaqBlock: React.FC<FaqBlockProps> = ({ 
+  title = "Häufig gestellte Fragen", 
+  subtitle, 
+  questions 
+}) => {
+  if (!questions || questions.length === 0) return null;
+
+  return (
+    <section className="py-12 md:py-16">
+      <div className="max-w-3xl mx-auto">
+        <div className="mb-10 text-center">
+          {subtitle && (
+            <span className="text-sm font-bold text-accent uppercase tracking-wider block mb-2">
+              {subtitle}
+            </span>
+          )}
+          <h2 className="text-3xl md:text-4xl font-bold text-text-primary">
+            {title}
+          </h2>
+        </div>
+        
+        <div className="space-y-4">
+          {questions.map((item, index) => (
+            <details 
+              key={index} 
+              className="group border border-neutral-200 bg-white rounded-xl overflow-hidden shadow-sm hover:shadow-md transition-shadow"
+            >
+              <summary className="flex items-center justify-between cursor-pointer p-6 font-semibold text-lg text-text-primary hover:text-primary transition-colors select-none">
+                {item.question}
+                <span className="ml-4 flex-shrink-0 transition-transform duration-300 group-open:-rotate-180 text-accent">
+                  <svg width="20" height="20" viewBox="0 0 20 20" fill="none" xmlns="http://www.w3.org/2000/svg">
+                    <path d="M5 7.5L10 12.5L15 7.5" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round"/>
+                  </svg>
+                </span>
+              </summary>
+              <div className="px-6 pb-6 text-text-secondary leading-relaxed border-t border-neutral-100 pt-4 prose prose-p:my-2 prose-a:text-primary">
+                {/* Parse simple HTML or just text if answer has formatting */}
+                <div dangerouslySetInnerHTML={{ __html: item.answer }} />
+              </div>
+            </details>
+          ))}
+        </div>
+      </div>
+      
+      {/* Inject FAQ Schema automatically */}
+      <JsonLd data={getFAQSchema(questions)} />
+    </section>
+  );
+};