feat(andreknie.de): improve accessibility and initial loading

privat/CV/andreknie.de/src/components/TestimonialSlider.jsx

@@ -123,10 +123,21 @@ export default function TestimonialSlider({ testimonials = [] }) {
     }
   }
 
+  const handleKeyDown = (event) => {
+    if (event.key === 'ArrowLeft') {
+      event.preventDefault()
+      scrollByCard(-1)
+    } else if (event.key === 'ArrowRight') {
+      event.preventDefault()
+      scrollByCard(1)
+    }
+  }
+
   if (testimonials.length === 0) return null
 
   return (
-    <section className="testimonials-section app-container">
+    <section className="testimonials-section app-container" aria-labelledby="testimonials-heading">
+      <h2 id="testimonials-heading" className="sr-only">Testimonials</h2>
       <div className="testimonial-slider-controls" aria-label="Testimonials wechseln">
         <button type="button" className="testimonial-nav-button" onClick={() => scrollByCard(-1)} aria-label="Vorheriges Testimonial">
           <ChevronLeft size={22} aria-hidden="true" />
@@ -138,6 +149,11 @@ export default function TestimonialSlider({ testimonials = [] }) {
       <div
         className={`testimonial-scroll-container${isDragging ? ' dragging' : ''}`}
         ref={scrollerRef}
+        role="region"
+        aria-label={`Testimonial ${testimonials.length > 1 ? 'Karussell' : ''}`}
+        aria-roledescription="Karussell"
+        tabIndex="0"
+        onKeyDown={handleKeyDown}
         onPointerDown={handlePointerDown}
         onPointerMove={handlePointerMove}
         onPointerUp={stopDragging}
@@ -147,7 +163,7 @@ export default function TestimonialSlider({ testimonials = [] }) {
         }}
       >
         {visibleTestimonials.map((current, i) => (
-          <div className="testimonial-card glass-panel" key={`${current.name}-${i}`}>
+          <div className="testimonial-card glass-panel" key={`${current.name}-${i}`} aria-hidden={canLoop && Math.floor(i / testimonials.length) !== MIDDLE_SET}>
             <div className="testimonial-quote">
               <span className="quote-mark">"</span>
               <p>{current.quote}</p>