Refactor expense chart title

Moves the expense chart title outside of the card component for better visual consistency.

src/components/ExpenseChart.tsx

@@ -1,6 +1,6 @@
 
 import React from 'react';
-import { PieChart, Pie, Cell, ResponsiveContainer, Legend } from 'recharts';
+import { PieChart, Pie, Cell, ResponsiveContainer } from 'recharts';
 
 interface ExpenseData {
   name: string;
@@ -15,9 +15,7 @@ interface ExpenseChartProps {
 const ExpenseChart: React.FC<ExpenseChartProps> = ({ data }) => {
   return (
     <div className="neuro-card h-64">
-      <h3 className="text-sm font-medium text-gray-600 mb-3">카테고리별 지출</h3>
-      
-      <ResponsiveContainer width="100%" height="85%">
+      <ResponsiveContainer width="100%" height="100%">
         <PieChart>
           <Pie
             data={data}