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/message-list.tsx

@@ -9,7 +9,7 @@ import { Button } from "@/shared/components/ui/button"
 import { Card, CardContent, CardHeader } from "@/shared/components/ui/card"
 import { EmptyState } from "@/shared/components/ui/empty-state"
 import { Tabs, TabsList, TabsTrigger } from "@/shared/components/ui/tabs"
-import { formatDate } from "@/shared/lib/utils"
+import { cn, formatDate } from "@/shared/lib/utils"
 import { usePermission } from "@/shared/hooks/use-permission"
 import { Permissions } from "@/shared/types/permissions"
 
@@ -79,7 +79,7 @@ export function MessageList({
             const unread = isReceived && !m.isRead
             return (
               <Link key={m.id} href={`/messages/${m.id}`} className="block">
-                <Card className={`transition-colors hover:bg-accent/50 ${unread ? "border-primary/40" : ""}`}>
+                <Card className={cn("transition-colors hover:bg-accent/50", unread && "border-primary/40")}>
                   <CardHeader className="flex flex-row items-start justify-between gap-2 space-y-0 pb-3">
                     <div className="space-y-1">
                       <div className="flex items-center gap-2">
@@ -88,7 +88,7 @@ export function MessageList({
                         ) : (
                           <MailOpen className="text-muted-foreground h-4 w-4" />
                         )}
-                        <span className={`text-sm font-medium ${unread ? "text-primary" : ""}`}>
+                        <span className={cn("text-sm font-medium", unread && "text-primary")}>
                           {m.subject ?? "(no subject)"}
                         </span>
                         {unread ? <Badge variant="default" className="text-xs">New</Badge> : null}