Widen Cost Structure section to match Container Matching width

Changed max-w-4xl to max-w-5xl for consistent layout.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/app/cost/page.tsx

@@ -331,7 +331,7 @@ export default function CostPage() {
       {/* Cost Structure */}
       <div className="bg-white py-12">
         <div className="container mx-auto px-4">
-          <div className="max-w-4xl mx-auto">
+          <div className="max-w-5xl mx-auto">
             <h2 className="text-2xl font-bold text-gray-800 text-center mb-8">{t.costTitle}</h2>
 
             <div className="grid grid-cols-1 md:grid-cols-2 gap-8">