chore: deep semantic HTML audit and improvements across all pages

components/ui/Card.tsx

@@ -1,10 +1,14 @@
 import React from 'react';
 import { cn } from './utils';
 
-export function Card({ className, children, ...props }: React.HTMLAttributes<HTMLDivElement>) {
+interface CardProps extends React.HTMLAttributes<HTMLElement> {
+  tag?: 'div' | 'article' | 'section' | 'aside' | 'header' | 'footer' | 'nav' | 'main';
+}
+
+export function Card({ className, children, tag: Tag = 'div', ...props }: CardProps) {
   return (
-    <div className={cn('premium-card overflow-hidden', className)} {...props}>
+    <Tag className={cn('premium-card overflow-hidden', className)} {...props}>
       {children}
-    </div>
+    </Tag>
   );
 }