feat: 新增备课模块并修复全模块 P0/P1/P2 缺陷

主要变更:

- 新增 lesson-preparation 模块: 备课编辑器、节点编辑、AI 建议、知识点选择、版本历史、作业发布

- 新增 shared 通用组件: charts/question-bank-filters/schedule-list/ui (chip-nav/filter-bar/page-header/stat-card/stat-item)

- 新增 student/admin 端 loading.tsx 与 error.tsx, 优化加载与错误态体验

- 新增 teacher/lesson-plans 页面 (列表/新建/编辑)

- 新增 drizzle 迁移 0002_tiny_lionheart 及 snapshot

- 新增 textbooks/schema.ts 与 exams/utils/normalize-structure.ts

- 修复 Tiptap v3 SSR hydration 崩溃 (rich-text-block immediatelyRender: false)

- 重构多模块 data-access/actions/组件, 修复权限校验与类型规范

- 同步架构文档 004/005 反映新增模块、导出、依赖关系

- 归档 bugs/* 测试报告与 e2e 测试脚本 (admin/parent/student/teacher web_test)

src/modules/messaging/components/notification-dropdown.tsx

@@ -16,14 +16,14 @@ import {
   DropdownMenuTrigger,
 } from "@/shared/components/ui/dropdown-menu"
 import { ScrollArea } from "@/shared/components/ui/scroll-area"
-import { formatDate } from "@/shared/lib/utils"
+import { cn, formatDate } from "@/shared/lib/utils"
 
 import {
   getNotificationsAction,
   markAllNotificationsAsReadAction,
   markNotificationAsReadAction,
 } from "../actions"
-import type { Notification, NotificationType } from "../types"
+import type { Notification, NotificationType } from "@/modules/notifications/types"
 
 const TYPE_ICON: Record<NotificationType, typeof Bell> = {
   message: MessageSquare,
@@ -131,7 +131,7 @@ export function NotificationDropdown() {
                       {!n.isRead ? (
                         <span className="bg-primary size-1.5 shrink-0 rounded-full" />
                       ) : null}
-                      <span className={`text-xs ${!n.isRead ? "font-semibold" : "font-medium"}`}>
+                      <span className={cn("text-xs", !n.isRead ? "font-semibold" : "font-medium")}>
                         {n.title}
                       </span>
                     </div>