Show expense input button label

Display "지출 입력" label on the add transaction button to improve clarity.

src/components/AddTransactionButton.tsx

@@ -128,12 +128,13 @@ const AddTransactionButton = () => {
     <>
       <div className="fixed bottom-24 right-6 z-20">
         <button 
-          className="p-4 rounded-full transition-all duration-300 bg-neuro-income shadow-neuro-flat hover:shadow-neuro-convex text-white animate-pulse-subtle"
+          className="flex items-center gap-2 px-4 py-3 rounded-full transition-all duration-300 bg-neuro-income shadow-neuro-flat hover:shadow-neuro-convex text-white animate-pulse-subtle"
           onClick={() => setShowExpenseDialog(true)}
           aria-label="지출 추가"
           disabled={isSubmitting}
         >
-          <PlusIcon size={24} />
+          <PlusIcon size={20} />
+          <span className="mr-1">지출 입력</span>
         </button>
       </div>