ux: 花名册操作优化 - 去掉发薪、开具证明/续签合同直接操作、删除用工办理页面

- 去掉花名册操作栏的"发薪"按钮
- 开具证明改为弹窗直接创建+提交，不再跳转用工办理页面
- 续签合同改为弹窗直接创建+提交，自动推导新合同开始日期
- 批量开具证明改为直接API调用，不再跳转用工办理页面
- 删除用工办理页面(WorkProcess.tsx)和路由
- 去掉工具栏"用工办理"按钮

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frontend/src/App.tsx

@@ -41,7 +41,6 @@ const MedicalPeriodCalculator = lazy(() => import('./pages/tools/MedicalPeriodCa
 const HealthCheck = lazy(() => import('./pages/tools/HealthCheck'))
 const AnnualValueReport = lazy(() => import('./pages/tools/AnnualValueReport'))
 const CalendarPage = lazy(() => import('./pages/Calendar'))
-const WorkProcess = lazy(() => import('./pages/WorkProcess'))
 const MyAttendance = lazy(() => import('./pages/portal/MyAttendance'))
 const MyLeave = lazy(() => import('./pages/portal/MyLeave'))
 const SpecialStatus = lazy(() => import('./pages/SpecialStatus'))
@@ -204,7 +203,6 @@ export default function App() {
       <Route path="/tools/medical-period" element={<ProtectedRoute><AdminLayout><MedicalPeriodCalculator /></AdminLayout></ProtectedRoute>} />
       <Route path="/tools/health-check" element={<ProtectedRoute><AdminLayout><HealthCheck /></AdminLayout></ProtectedRoute>} />
       <Route path="/tools/annual-value" element={<ProtectedRoute><AdminLayout><AnnualValueReport /></AdminLayout></ProtectedRoute>} />
-      <Route path="/work-process" element={<ProtectedRoute><AdminLayout><WorkProcess /></AdminLayout></ProtectedRoute>} />
       <Route path="/special-status" element={<ProtectedRoute><AdminLayout><SpecialStatus /></AdminLayout></ProtectedRoute>} />
       <Route path="/company-files" element={<ProtectedRoute><AdminLayout><CompanyFiles /></AdminLayout></ProtectedRoute>} />
       <Route path="/leave-approval" element={<ProtectedRoute><AdminLayout><LeaveApproval /></AdminLayout></ProtectedRoute>} />