Fix budget display issues

Addresses issues where budget data wasn't displaying correctly after input and ensures correct automatic calculation of daily/weekly budgets from monthly input.

src/components/BudgetTabContent.tsx

@@ -34,7 +34,7 @@ const BudgetTabContent: React.FC<BudgetTabContentProps> = ({
   const percentage = actualPercentage;
   
   // 예산이 설정되었는지 여부 확인 (정확히 0이면 미설정으로 간주)
-  const isBudgetSet = targetAmount !== 0;
+  const isBudgetSet = targetAmount > 0;
 
   // 예산 초과 여부 계산
   const isOverBudget = spentAmount > targetAmount && targetAmount > 0;