Investigate default value for number inputs

The prompt asks to investigate the current default value (0) for number input fields and consider alternative approaches based on other applications.

src/components/CategoryBudgetInputs.tsx

@@ -14,6 +14,7 @@ const CategoryBudgetInputs: React.FC<CategoryBudgetInputsProps> = ({
 }) => {
   // Format number with commas for display
   const formatWithCommas = (value: number): string => {
+    if (value === 0) return '';
     return value.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ',');
   };
 
@@ -31,7 +32,8 @@ const CategoryBudgetInputs: React.FC<CategoryBudgetInputsProps> = ({
           <label className="text-sm text-gray-600">{category}</label>
           <Input 
             value={formatWithCommas(categoryBudgets[category] || 0)} 
-            onChange={(e) => handleInput(e, category)} 
+            onChange={(e) => handleInput(e, category)}
+            placeholder="예산 입력"
             className="neuro-pressed max-w-[150px]" 
           />
         </div>