Fix budget display issue

The budget display in the budget card was not showing correctly when the budget was not set. This commit fixes the issue.

src/components/BudgetTabContent.tsx

@@ -32,10 +32,12 @@ const BudgetTabContent: React.FC<BudgetTabContentProps> = ({
   // 실제 백분율 계산 (초과해도 실제 퍼센트로 표시)
   const actualPercentage = targetAmount > 0 ? Math.round(spentAmount / targetAmount * 100) : 0;
   const percentage = actualPercentage;
-  const isFirstBudget = targetAmount === 0;
+  
+  // 예산이 설정되었는지 여부 확인 (0이면 미설정으로 간주)
+  const isBudgetSet = targetAmount > 0;
 
   // 예산 초과 여부 계산
-  const isOverBudget = spentAmount > targetAmount;
+  const isOverBudget = spentAmount > targetAmount && targetAmount > 0;
   // 예산이 얼마 남지 않은 경우 (10% 미만)
   const isLowBudget = targetAmount > 0 && percentage >= 90 && percentage < 100;
 
@@ -108,11 +110,11 @@ const BudgetTabContent: React.FC<BudgetTabContentProps> = ({
   };
 
   // 예산 여부에 따른 텍스트 결정
-  const budgetButtonText = targetAmount > 0 ? "예산 수정하기" : "예산 입력하기";
+  const budgetButtonText = isBudgetSet ? "예산 수정하기" : "예산 입력하기";
 
   return (
     <div>
-      {targetAmount > 0 ? (
+      {isBudgetSet ? (
         <>
           <div className="flex justify-between items-center mb-3">
             <div className="text-base font-bold">{formatCurrency(spentAmount)}</div>