Revert to three expense categories

Reverted the number of expense categories back to the original three. Future feature additions or changes will require confirmation.

src/components/transaction/TransactionFormFields.tsx

@@ -6,11 +6,11 @@ import { UseFormReturn } from 'react-hook-form';
 import { z } from 'zod';
 import { categoryIcons, EXPENSE_CATEGORIES } from '@/constants/categoryIcons';
 
-// Form schema for validation
+// Form schema for validation - 카테고리를 3개로 축소
 export const transactionFormSchema = z.object({
   title: z.string().min(1, '제목을 입력해주세요'),
   amount: z.string().min(1, '금액을 입력해주세요'),
-  category: z.enum(['식비', '생활비', '교통비', '쇼핑', '교육', '의료', '여행', '기타']),
+  category: z.enum(['식비', '생활비', '교통비']),
 });
 
 export type TransactionFormValues = z.infer<typeof transactionFormSchema>;