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/app/(dashboard)/teacher/classes/students/page.tsx

@@ -1,3 +1,4 @@
+import type { JSX } from "react"
 import { Suspense } from "react"
 import { User } from "lucide-react"
 
@@ -6,17 +7,11 @@ import { StudentsFilters } from "@/modules/classes/components/students-filters"
 import { StudentsTable } from "@/modules/classes/components/students-table"
 import { EmptyState } from "@/shared/components/ui/empty-state"
 import { Skeleton } from "@/shared/components/ui/skeleton"
+import { getParam, type SearchParams } from "@/shared/lib/search-params"
 
 export const dynamic = "force-dynamic"
 
-type SearchParams = { [key: string]: string | string[] | undefined }
-
-const getParam = (params: SearchParams, key: string) => {
-  const v = params[key]
-  return Array.isArray(v) ? v[0] : v
-}
-
-async function StudentsResults({ searchParams, defaultClassId }: { searchParams: Promise<SearchParams>, defaultClassId?: string }) {
+async function StudentsResults({ searchParams, defaultClassId }: { searchParams: Promise<SearchParams>, defaultClassId?: string }): Promise<JSX.Element> {
   const params = await searchParams
 
   const q = getParam(params, "q") || undefined
@@ -80,7 +75,7 @@ function StudentsResultsFallback() {
   )
 }
 
-export default async function StudentsPage({ searchParams }: { searchParams: Promise<SearchParams> }) {
+export default async function StudentsPage({ searchParams }: { searchParams: Promise<SearchParams> }): Promise<JSX.Element> {
   const classes = await getTeacherClasses()
   
   // Logic to determine default class (first one available)