refactor: AdminSchedule, AdminScheduleForm 날짜 파싱에 formatDate 유틸리티 적용

- AdminSchedule.jsx: hasSchedule, getScheduleColor, filteredSchedules에서 formatDate 사용
- AdminScheduleForm.jsx: 수정 모드 날짜 로드 시 formatDate 사용
- toISOString 대신 dayjs 기반 formatDate 사용

frontend/src/pages/pc/admin/AdminSchedule.jsx

@@ -11,7 +11,7 @@ import { useInView } from 'react-intersection-observer';
 import Toast from '../../../components/Toast';
 import Tooltip from '../../../components/Tooltip';
 import useScheduleStore from '../../../stores/useScheduleStore';
-import { getTodayKST } from '../../../utils/date';
+import { getTodayKST, formatDate } from '../../../utils/date';
 
 function AdminSchedule() {
     const navigate = useNavigate();
@@ -170,7 +170,7 @@ function AdminSchedule() {
     const hasSchedule = (day) => {
         const dateStr = `${year}-${String(month + 1).padStart(2, '0')}-${String(day).padStart(2, '0')}`;
         return schedules.some(s => {
-            const scheduleDate = new Date(s.date).toISOString().split('T')[0];
+            const scheduleDate = formatDate(s.date);
             return scheduleDate === dateStr;
         });
     };
@@ -179,7 +179,7 @@ function AdminSchedule() {
     const getScheduleColor = (day) => {
         const dateStr = `${year}-${String(month + 1).padStart(2, '0')}-${String(day).padStart(2, '0')}`;
         const schedule = schedules.find(s => {
-            const scheduleDate = new Date(s.date).toISOString().split('T')[0];
+            const scheduleDate = formatDate(s.date);
             return scheduleDate === dateStr;
         });
         if (!schedule) return null;
@@ -394,7 +394,7 @@ function AdminSchedule() {
         ? (searchTerm ? searchResults : [])  // 검색 모드: 검색 전엔 빈 목록, 검색 후엔 API 결과
         : schedules.filter(schedule => {  // 일반 모드: 로컬 필터링
             const matchesCategory = selectedCategories.length === 0 || selectedCategories.includes(schedule.category_id);
-            const scheduleDate = new Date(schedule.date).toISOString().split('T')[0];
+            const scheduleDate = formatDate(schedule.date);
             const matchesDate = !selectedDate || scheduleDate === selectedDate;
             return matchesCategory && matchesDate;
         });

frontend/src/pages/pc/admin/AdminScheduleForm.jsx

@@ -1,6 +1,7 @@
 import { useState, useEffect, useRef } from "react";
 import { useNavigate, Link, useParams } from "react-router-dom";
 import { motion, AnimatePresence } from "framer-motion";
+import { formatDate } from "../../../utils/date";
 import {
   LogOut,
   Home,
@@ -898,12 +899,8 @@ function AdminScheduleForm() {
       // 폼 데이터 설정
       setFormData({
         title: data.title || "",
-        startDate: data.date
-          ? new Date(data.date).toISOString().split("T")[0]
-          : "",
-        endDate: data.end_date
-          ? new Date(data.end_date).toISOString().split("T")[0]
-          : "",
+        startDate: data.date ? formatDate(data.date) : "",
+        endDate: data.end_date ? formatDate(data.end_date) : "",
         startTime: data.time?.slice(0, 5) || "",
         endTime: data.end_time?.slice(0, 5) || "",
         isRange: !!data.end_date,