feat(WEB): CEO 대시보드 캘린더 강화 및 validation 모듈 분리

- CalendarSection 일정 CRUD 기능 확장 (상세 모달 연동)
- ScheduleDetailModal 개선
- CEO 대시보드 섹션별 API 키 통일
- validation.ts → validation/ 모듈 분리 (item-schemas, utils)
- formatters.ts 확장
- date.ts 유틸 추가
- SignupPage/EmployeeForm/AddCompanyDialog 등 소규모 개선
- PaymentHistory/PopupManagement utils 정리

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/components/settings/CompanyInfoManagement/AddCompanyDialog.tsx

@@ -20,6 +20,7 @@ import {
   AlertDialogHeader,
   AlertDialogTitle,
 } from '@/components/ui/alert-dialog';
+import { extractDigits } from '@/lib/formatters';
 
 interface AddCompanyDialogProps {
   open: boolean;
@@ -36,7 +37,7 @@ export function AddCompanyDialog({ open, onOpenChange }: AddCompanyDialogProps)
 
   // 숫자만 입력 가능 (10자리 제한)
   const handleBusinessNumberChange = (value: string) => {
-    const numbersOnly = value.replace(/[^0-9]/g, '');
+    const numbersOnly = extractDigits(value);
     if (numbersOnly.length <= 10) {
       setBusinessNumber(numbersOnly);
     }

src/components/settings/PaymentHistoryManagement/utils.ts

@@ -1,6 +1,6 @@
 import type { PaymentApiData, PaymentHistory, PaymentStatus } from './types';
 import { PAYMENT_METHOD_LABELS } from './types';
-import { formatDate } from '@/lib/utils/date';
+import { formatDate, toDateString } from '@/lib/utils/date';
 
 // ===== API → Frontend 변환 =====
 export function transformApiToFrontend(apiData: PaymentApiData): PaymentHistory {
@@ -11,12 +11,12 @@ export function transformApiToFrontend(apiData: PaymentApiData): PaymentHistory
   const paymentMethodLabel = PAYMENT_METHOD_LABELS[apiData.payment_method] || apiData.payment_method;
 
   // 구독 기간
-  const periodStart = subscription?.started_at?.split('T')[0] || '';
-  const periodEnd = subscription?.ended_at?.split('T')[0] || '';
+  const periodStart = toDateString(subscription?.started_at);
+  const periodEnd = toDateString(subscription?.ended_at);
 
   return {
     id: String(apiData.id),
-    paymentDate: apiData.paid_at?.split('T')[0] || formatDate(apiData.created_at),
+    paymentDate: toDateString(apiData.paid_at) || formatDate(apiData.created_at),
     subscriptionName: plan?.name || '구독',
     paymentMethod: paymentMethodLabel,
     subscriptionPeriod: {

src/components/settings/PopupManagement/utils.ts

@@ -3,6 +3,7 @@
  */
 
 import type { Popup, PopupFormData, PopupTarget, PopupStatus } from './types';
+import { toDateString } from '@/lib/utils/date';
 
 // ============================================
 // API 응답 타입 정의
@@ -55,9 +56,9 @@ export function transformApiToFrontend(apiData: PopupApiData): Popup {
     status: apiData.status as PopupStatus,
     author: apiData.creator?.name || '관리자',
     authorId: apiData.created_by ? String(apiData.created_by) : '',
-    createdAt: apiData.created_at?.split('T')[0] || '',
-    startDate: apiData.started_at?.split('T')[0] || '',
-    endDate: apiData.ended_at?.split('T')[0] || '',
+    createdAt: toDateString(apiData.created_at),
+    startDate: toDateString(apiData.started_at),
+    endDate: toDateString(apiData.ended_at),
   };
 }