feat: 품목정보 상세 패널 추가 및 프로젝트/근태/권한 기능 확장

- Items: 우측에 이미지, 담당자, 입고/발주내역 패널 추가 (fItems 윈폼 동일)
- Project: 목록 및 상세 다이얼로그 구현
- Kuntae: 오류검사/수정 기능 추가
- UserAuth: 사용자 권한 관리 페이지 추가
- UserGroup: 그룹정보 다이얼로그로 전환
- Header: 사용자 메뉴 서브메뉴 방향 수정, 즐겨찾기 기능
- Backend API: Items 상세/담당자/구매내역, 근태 오류검사, 프로젝트 목록 등

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Project/frontend/src/App.tsx

@@ -1,7 +1,7 @@
 import { useState, useEffect } from 'react';
 import { HashRouter, Routes, Route } from 'react-router-dom';
 import { Layout } from '@/components/layout';
-import { Dashboard, Todo, Kuntae, Jobreport, PlaceholderPage, Login, CommonCodePage, ItemsPage, UserListPage, MonthlyWorkPage, MailFormPage, UserGroupPage } from '@/pages';
+import { Dashboard, Todo, Kuntae, Jobreport, Project, Login, CommonCodePage, ItemsPage, UserListPage, MonthlyWorkPage, MailFormPage, UserAuthPage } from '@/pages';
 import { comms } from '@/communication';
 import { UserInfo } from '@/types';
 import { Loader2 } from 'lucide-react';
@@ -85,15 +85,24 @@ export default function App() {
           <Route path="/todo" element={<Todo />} />
           <Route path="/kuntae" element={<Kuntae />} />
           <Route path="/jobreport" element={<Jobreport />} />
-          <Route path="/project" element={<PlaceholderPage title="프로젝트" />} />
+          <Route path="/project" element={<Project />} />
           <Route path="/common" element={<CommonCodePage />} />
           <Route path="/items" element={<ItemsPage />} />
           <Route path="/user/list" element={<UserListPage />} />
+          <Route path="/user/auth" element={<UserAuthPage />} />
           <Route path="/monthly-work" element={<MonthlyWorkPage />} />
           <Route path="/mail-form" element={<MailFormPage />} />
-          <Route path="/user-group" element={<UserGroupPage />} />
         </Route>
       </Routes>
+      {/* Tailwind Breakpoint Indicator - 개발용 */}
+      <div className="fixed bottom-2 right-2 z-50 bg-black/80 text-white text-xs px-2 py-1 rounded font-mono">
+        <span className="sm:hidden">XS</span>
+        <span className="hidden sm:inline md:hidden">SM</span>
+        <span className="hidden md:inline lg:hidden">MD</span>
+        <span className="hidden lg:inline xl:hidden">LG</span>
+        <span className="hidden xl:inline 2xl:hidden">XL</span>
+        <span className="hidden 2xl:inline">2XL</span>
+      </div>
     </HashRouter>
   );
 }