style: change comparison images to vertical layout

- Switch from side-by-side to stacked vertical layout
- Display images at full container width (same as videos)
- Increase spacing between images for better readability
- Each image now spans the full content area

Author: daijun10086

src/App.tsx

@@ -556,7 +556,7 @@ function App() {
         {/* Qualitative Comparisons */}
         <section className="mb-20">
           <h2 className="font-serif text-3xl font-semibold mb-8 text-slate-900">Qualitative Comparisons</h2>
-          <div className="grid grid-cols-1 lg:grid-cols-2 gap-8">
+          <div className="space-y-10">
             {/* Real-world comparison */}
             <div>
               <img