feat(app): add error/loading boundaries and update dashboard routes

- Add error.tsx and loading.tsx boundaries for admin, parent, student, teacher routes

- Add dashboard-error-fallback and dashboard-loading-skeleton components

- Add student/learning page, parent/leave routes, teacher textbook components

- Update existing app routes across auth, dashboard, and API endpoints

- Update proxy middleware and next-auth type declarations

src/app/api/search/route.ts

@@ -1,7 +1,7 @@
 import { NextResponse } from "next/server"
 import { and, desc, eq, like, or, sql } from "drizzle-orm"
 
-import { requireAuth } from "@/shared/lib/auth-guard"
+import { getAuthContext } from "@/shared/lib/auth-guard"
 import { db } from "@/shared/db"
 import {
   announcements,
@@ -41,10 +41,12 @@ interface SearchResponse {
 /**
  * GET /api/search?q=keyword&type=all&page=1
  * 全文检索：questions / textbooks / exams / announcements
+ * 按角色过滤：学生只能搜索 textbook 和 announcement
  */
 export async function GET(req: Request) {
   try {
-    await requireAuth()
+    const ctx = await getAuthContext()
+    const isStudent = ctx.roles.includes("student") && !ctx.roles.includes("admin") && !ctx.roles.includes("teacher")
 
     const { searchParams } = new URL(req.url)
     const q = (searchParams.get("q") ?? "").trim()
@@ -72,16 +74,18 @@ export async function GET(req: Request) {
     const offset = (page - 1) * pageSize
     const results: SearchResultItem[] = []
 
-    // 并行查询各类型
+    // 并行查询各类型（按角色过滤）
     const tasks: Promise<SearchResultItem[]>[] = []
 
-    if (type === "all" || type === "question") {
+    // 学生不能搜索题目和考试
+    if (!isStudent && (type === "all" || type === "question")) {
       tasks.push(searchQuestions(kw, pageSize))
     }
     if (type === "all" || type === "textbook") {
       tasks.push(searchTextbooks(kw, pageSize))
     }
-    if (type === "all" || type === "exam") {
+    // 学生不能搜索考试
+    if (!isStudent && (type === "all" || type === "exam")) {
       tasks.push(searchExams(kw, pageSize))
     }
     if (type === "all" || type === "announcement") {