✨ feat: enhance accessibility with skip to main content button and improve navigation handling

🔧 fix: update navigation href resolution to include localized paths

🆕 feat: add new FeatureIcon component for feature boxes

🎨 style: improve styling for prose elements in richtext blocks

🛠️ refactor: streamline medialib image loading and caching logic

📦 chore: update mock data handling to support new medialib entries

🔄 chore: synchronize i18n initialization and locale management

📝 docs: update video tour descriptions to reflect recent changes

frontend/assets/img/placeholder-image.svg

@@ -0,0 +1,16 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1200 900" role="img" aria-labelledby="title desc">
+  <title id="title">Placeholder image</title>
+  <desc id="desc">Neutral placeholder graphic for missing media assets.</desc>
+  <defs>
+    <linearGradient id="bg" x1="0" y1="0" x2="1" y2="1">
+      <stop offset="0%" stop-color="#e5eef6" />
+      <stop offset="100%" stop-color="#cfdcea" />
+    </linearGradient>
+  </defs>
+  <rect width="1200" height="900" fill="url(#bg)" />
+  <g fill="none" stroke="#7c97b2" stroke-width="28" stroke-linecap="round" stroke-linejoin="round">
+    <rect x="120" y="120" width="960" height="660" rx="36" />
+    <path d="M220 650l190-190 140 140 170-210 260 260" />
+    <circle cx="410" cy="310" r="70" />
+  </g>
+</svg>