[Hotfix/#109] Response Entity Type 수정 (#113)

* [Refactor] #109 계좌 번호를 받아 잔액을 반환하도록 변경

* [Refactor]

* [Feat] #109 Add DTOs

* [Fix] #109 Respose Type 변ã�경

src/main/java/com/shinhan_hackathon/the_family_guardian/domain/transaction/controller/TransactionController.java

@@ -1,5 +1,6 @@
 package com.shinhan_hackathon.the_family_guardian.domain.transaction.controller;
 
+import com.shinhan_hackathon.the_family_guardian.domain.transaction.dto.AccountBalanceResponse;
 import com.shinhan_hackathon.the_family_guardian.domain.transaction.dto.DepositRequest;
 import com.shinhan_hackathon.the_family_guardian.domain.transaction.dto.PaymentRequest;
 import com.shinhan_hackathon.the_family_guardian.domain.transaction.dto.AccountBalanceRequest;
@@ -79,7 +80,7 @@ public ResponseEntity<Void> updatePayment(@RequestBody PaymentRequest paymentReq
 
 	// TODO: 잔액 조회
 	@PostMapping("/balance")
-	public ResponseEntity<?> getTransactionBalance(@RequestBody AccountBalanceRequest accountBalanceRequest) {
+	public ResponseEntity<AccountBalanceResponse> getTransactionBalance(@RequestBody AccountBalanceRequest accountBalanceRequest) {
 		log.info("TransactionController.getTransactionBalance() is called.");
 
 		return ResponseEntity.ok(transactionService.findByAccountNumber(accountBalanceRequest));