refactor(web-ui): Apply modular structure and refactor dashboard

This commit applies the modular refactoring to the web-ui,
including the new daily attendance tracking feature.

- **Modular Structure:** Re-introduced the modular files 'config.js',
  'component-loader.js', and 'navigation.js' to centralize configuration,
  component loading, and navigation logic.
- **Refactored Dashboard:** Refactored 'group-leader-dashboard.js' to use
  the new 'apiCall' function from 'api-config.js' for API requests,
  removing duplicated code and improving error handling.
- **ES6 Modules:** Updated 'group-leader.html' to load scripts as
  ES6 modules ('type="module"'), ensuring compatibility with the
  modular JavaScript files.
- **Clean-up:** Removed unnecessary global variables and duplicated
  functions, improving code quality and maintainability.

web-ui/js/group-leader-dashboard.js

@@ -1,5 +1,6 @@
 // /js/group-leader-dashboard.js
 // 그룹장 전용 대시보드 - 실시간 근태 및 작업 현황 (Real Data Version)
+import { apiCall } from './api-config.js';
 
 console.log('📊 그룹장 대시보드 스크립트 로딩 (Live Data)');
 
@@ -54,13 +55,7 @@ async function loadDailyWorkStatus() {
   `;
 
   try {
-    const response = await fetch(`${window.API_BASE_URL}/attendance/daily-status?date=${currentSelectedDate}`, {
-      headers: getAuthHeaders()
-    });
-
-    if (!response.ok) throw new Error('데이터 로드 실패');
-
-    const result = await response.json();
+    const result = await apiCall(`/attendance/daily-status?date=${currentSelectedDate}`);
     const workers = result.data || [];
 
     renderWorkStatus(workers);
@@ -143,15 +138,6 @@ function renderWorkStatus(workers) {
   container.innerHTML = html;
 }
 
-// 🔐 인증 헤더 헬퍼
-function getAuthHeaders() {
-  const token = localStorage.getItem('token');
-  return {
-    'Authorization': `Bearer ${token}`,
-    'Content-Type': 'application/json'
-  };
-}
-
 // 🍞 토스트 메시지 (기존 modern-dashboard.js에 있다면 중복 주의, 없으면 사용)
 function showToast(message, type = 'info') {
   if (window.showToast) {
@@ -163,12 +149,9 @@ function showToast(message, type = 'info') {
 
 // 초기화
 document.addEventListener('DOMContentLoaded', () => {
-  // API_BASE_URL 설정 (없으면 기본값)
-  if (!window.API_BASE_URL) window.API_BASE_URL = '/api';
-
   initDateSelector();
   loadDailyWorkStatus();
 });
 
-// 전역 노출
-window.refreshTeamStatus = loadDailyWorkStatus;
+// 전역 노출 대신 모듈로 내보내기
+export { loadDailyWorkStatus as refreshTeamStatus };