feat(ui): update search component and improve responsive design

- Show only search icon on mobile (< 768px) in navbar
- Refactor Anchor component with better type safety and link handling
- Adjust spacing in Table of Contents and main content
- Improve responsive layout and consistency

app/docs/layout.tsx

@@ -8,7 +8,7 @@ export default function DocsLayout({
   return (
     <div className="flex items-start gap-8">
       <Leftbar key="leftbar" />
-      <div className="flex-[5.25] py-4 px-1">
+      <div className="flex-[5.25] px-1">
         {children}
       </div>
     </div>