fix(frontend): useCalendar 및 Schedule 날짜 처리 버그 수정

- useCalendar: initialDate가 문자열일 경우 Date 객체로 변환
- useCalendar: days 배열 추가 (캘린더 날짜 목록)
- useCalendar: canGoPrev 별칭 추가
- Schedule: currentDate가 Date 객체가 아닐 경우 안전하게 변환

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend-temp/src/hooks/useCalendar.js

@@ -5,10 +5,17 @@ import { getTodayKST } from '@/utils';
 /**
  * 캘린더 훅
  * 날짜 선택, 월 이동 등 캘린더 로직 제공
- * @param {Date} initialDate - 초기 날짜
+ * @param {Date|string} initialDate - 초기 날짜
  */
 export function useCalendar(initialDate = new Date()) {
-  const [currentDate, setCurrentDate] = useState(initialDate);
+  // initialDate가 Date 객체가 아니면 변환
+  const ensureDate = (date) => {
+    if (date instanceof Date) return date;
+    if (typeof date === 'string') return new Date(date);
+    return new Date();
+  };
+
+  const [currentDate, setCurrentDate] = useState(() => ensureDate(initialDate));
   const [selectedDate, setSelectedDate] = useState(getTodayKST());
 
   const year = currentDate.getFullYear();
@@ -20,6 +27,37 @@ export function useCalendar(initialDate = new Date()) {
     const daysInMonth = new Date(year, month + 1, 0).getDate();
     const prevMonthDays = new Date(year, month, 0).getDate();
 
+    // 캘린더에 표시할 날짜 배열 생성
+    const days = [];
+
+    // 이전 달 날짜
+    for (let i = firstDay - 1; i >= 0; i--) {
+      days.push({
+        day: prevMonthDays - i,
+        isCurrentMonth: false,
+        date: new Date(year, month - 1, prevMonthDays - i),
+      });
+    }
+
+    // 현재 달 날짜
+    for (let i = 1; i <= daysInMonth; i++) {
+      days.push({
+        day: i,
+        isCurrentMonth: true,
+        date: new Date(year, month, i),
+      });
+    }
+
+    // 다음 달 날짜 (6주 채우기)
+    const remaining = 42 - days.length; // 6주 * 7일 = 42
+    for (let i = 1; i <= remaining; i++) {
+      days.push({
+        day: i,
+        isCurrentMonth: false,
+        date: new Date(year, month + 1, i),
+      });
+    }
+
     return {
       year,
       month,
@@ -28,6 +66,7 @@ export function useCalendar(initialDate = new Date()) {
       daysInMonth,
       prevMonthDays,
       weekdays: WEEKDAYS,
+      days,
     };
   }, [year, month]);
 
@@ -93,6 +132,7 @@ export function useCalendar(initialDate = new Date()) {
     ...calendarData,
     currentDate,
     selectedDate,
+    canGoPrev: canGoPrevMonth,
     canGoPrevMonth,
     goToPrevMonth,
     goToNextMonth,

frontend-temp/src/pages/schedule/Schedule.jsx

@@ -143,11 +143,12 @@ function Schedule() {
   const isMobile = useIsMobile();
 
   // Zustand store
-  const { currentDate, setCurrentDate, selectedDate, setSelectedDate } = useScheduleStore();
+  const { currentDate: storedCurrentDate, setCurrentDate, selectedDate, setSelectedDate } = useScheduleStore();
 
-  // 초기값 설정
+  // 초기값 설정 - currentDate가 Date 객체가 아닐 수 있으므로 안전하게 변환
   const today = getTodayKST();
   const actualSelectedDate = selectedDate || today;
+  const currentDate = storedCurrentDate instanceof Date ? storedCurrentDate : new Date(storedCurrentDate || today);
 
   // 데이터 로드
   const year = currentDate.getFullYear();