feat(dashboard,diagnostic,elective): add widgets, layout, parent dashboard, role-config, services, elective components

dashboard:

- Add comparison-badge, dashboard-notification-widget, dashboard-responsive-layout, dashboard-time-range-filter

- Add parent-dashboard components directory

- Add config, hooks, and services directories

diagnostic:

- Add role-config and services directory

elective:

- Add elective-course-detail, elective-stats-cards, parent-selection-view components

- Add data-access-settings and data-access-stats

src/modules/dashboard/data-access.ts

@@ -43,6 +43,8 @@ export const getAdminDashboardData = cache(async (scope?: DataScope): Promise<Ad
     homeworkSubmissionCount: homeworkStats.homeworkSubmissionCount,
     homeworkSubmissionToGradeCount: homeworkStats.homeworkSubmissionToGradeCount,
     recentUsers: usersStats.recentUsers,
+    // TODO(V4-P2-4): 接入真实趋势数据统计查询（按日期聚合用户注册数和作业提交数）
+    // 当前为占位空数组，AdminTrendCharts 组件会渲染空状态
     userGrowth: [],
     homeworkTrend: [],
   }