feat(admin): 补全 admin 模块核心功能与产品体验优化

修复 v4 报告中的 13 个产品体验问题：新增用户管理列表页和系统设置页，重组导航菜单并补充缺失入口，增加角色切换机制，Dashboard 增加快捷操作和 recharts 趋势图表，考勤增加统计概览，排课增加课表网格视图，统一 Toast 操作反馈，同步更新架构文档

src/app/(dashboard)/admin/attendance/page.tsx

@@ -9,8 +9,9 @@ import { requirePermission, getAuthContext } from "@/shared/lib/auth-guard"
 import { Permissions } from "@/shared/types/permissions"
 import { getSearchParam, type SearchParams } from "@/shared/lib/utils"
 import { getAdminClasses } from "@/modules/classes/data-access"
-import { getAttendanceRecords } from "@/modules/attendance/data-access"
+import { getAttendanceRecords, getAttendanceStats } from "@/modules/attendance/data-access"
 import { AttendanceFilters } from "@/modules/attendance/components/attendance-filters"
+import { AttendanceStatsCards } from "@/modules/attendance/components/attendance-stats-cards"
 import { AttendanceRecordList } from "@/modules/attendance/components/attendance-record-list"
 import type { AttendanceStatus } from "@/modules/attendance/types"
 
@@ -50,6 +51,13 @@ export default async function AdminAttendancePage({
     date: date && date.length > 0 ? date : undefined,
   })
 
+  const stats = await getAttendanceStats({
+    scope: ctx.dataScope,
+    currentUserId: ctx.userId,
+    classId: classId && classId !== "all" ? classId : undefined,
+    date: date && date.length > 0 ? date : undefined,
+  })
+
   return (
     <div className="h-full flex-1 flex-col space-y-8 p-8 md:flex">
       <div className="flex items-center justify-between space-y-2">
@@ -65,6 +73,8 @@ export default async function AdminAttendancePage({
         </Button>
       </div>
 
+      <AttendanceStatsCards stats={stats} />
+
       <AttendanceFilters classes={classOptions} />
 
       {result.items.length === 0 && !classId && !status && !date ? (

src/app/(dashboard)/admin/scheduling/changes/page.tsx

@@ -3,15 +3,19 @@ import { PlusCircle, ClipboardList } from "lucide-react"
 import type { Metadata } from "next"
 import type { JSX } from "react"
 
+import { requirePermission } from "@/shared/lib/auth-guard"
+import { Permissions } from "@/shared/types/permissions"
 import { Button } from "@/shared/components/ui/button"
 import { EmptyState } from "@/shared/components/ui/empty-state"
 import { getSearchParam, type SearchParams } from "@/shared/lib/utils"
 import {
   getAdminClassesForScheduling,
   getScheduleChanges,
+  getScheduleEntriesForAdmin,
 } from "@/modules/scheduling/data-access"
 import { ScheduleChangeList } from "@/modules/scheduling/components/schedule-change-list"
 import { ScheduleConflictsView } from "@/modules/scheduling/components/schedule-conflicts-view"
+import { ScheduleGridView } from "@/modules/scheduling/components/schedule-grid-view"
 import type { ScheduleChangeStatus } from "@/modules/scheduling/types"
 
 export const metadata: Metadata = {
@@ -29,15 +33,17 @@ export default async function AdminSchedulingChangesPage({
 }: {
   searchParams: Promise<SearchParams>
 }): Promise<JSX.Element> {
+  await requirePermission(Permissions.SCHEDULE_ADJUST)
   const sp = await searchParams
   const statusParam = getSearchParam(sp, "status")
   const status = isValidStatus(statusParam) ? statusParam : undefined
   const classIdParam = getSearchParam(sp, "classId")
   const classId = classIdParam && classIdParam !== "all" ? classIdParam : undefined
 
-  const [classes, items] = await Promise.all([
+  const [classes, items, scheduleEntries] = await Promise.all([
     getAdminClassesForScheduling(),
     getScheduleChanges({ status, classId }),
+    getScheduleEntriesForAdmin(),
   ])
   const classOptions = classes.map((c) => ({ id: c.id, name: c.name, grade: c.grade }))
 
@@ -87,6 +93,14 @@ export default async function AdminSchedulingChangesPage({
           <ScheduleConflictsView classes={classOptions} />
         )}
       </div>
+
+      <div className="space-y-2">
+        <h3 className="text-lg font-semibold">课表网格</h3>
+        <p className="text-sm text-muted-foreground">
+          按班级查看当前课表分布。
+        </p>
+        <ScheduleGridView entries={scheduleEntries} classes={classOptions} />
+      </div>
     </div>
   )
 }

src/app/(dashboard)/admin/settings/page.tsx

@@ -0,0 +1,22 @@
+import type { Metadata } from "next"
+import type { JSX } from "react"
+
+import { requirePermission } from "@/shared/lib/auth-guard"
+import { Permissions } from "@/shared/types/permissions"
+import { AdminSettingsView } from "@/modules/settings/components/admin-settings-view"
+
+export const metadata: Metadata = {
+  title: "系统设置 - Next_Edu",
+  description: "管理系统基础信息与运行参数",
+}
+
+export const dynamic = "force-dynamic"
+
+export default async function AdminSettingsPage(): Promise<JSX.Element> {
+  await requirePermission(Permissions.SETTINGS_ADMIN)
+  return (
+    <div className="flex h-full flex-col p-8">
+      <AdminSettingsView />
+    </div>
+  )
+}

src/app/(dashboard)/admin/users/page.tsx

@@ -0,0 +1,48 @@
+import type { Metadata } from "next"
+import type { JSX } from "react"
+
+import { requirePermission } from "@/shared/lib/auth-guard"
+import { Permissions } from "@/shared/types/permissions"
+import { getSearchParam, type SearchParams } from "@/shared/lib/utils"
+import { getAdminUsers, getAdminUserRoles } from "@/modules/users/data-access"
+import { AdminUsersView } from "@/modules/users/components/admin-users-view"
+
+export const metadata: Metadata = {
+  title: "用户管理 - Next_Edu",
+  description: "管理系统所有用户",
+}
+
+export const dynamic = "force-dynamic"
+
+export default async function AdminUsersPage({
+  searchParams,
+}: {
+  searchParams: Promise<SearchParams>
+}): Promise<JSX.Element> {
+  await requirePermission(Permissions.USER_MANAGE)
+
+  const sp = await searchParams
+  const page = Number(getSearchParam(sp, "page") ?? "1") || 1
+  const search = getSearchParam(sp, "search") ?? ""
+  const role = getSearchParam(sp, "role") ?? ""
+
+  const [result, roleOptions] = await Promise.all([
+    getAdminUsers({ page, search: search || undefined, role: role || undefined }),
+    getAdminUserRoles(),
+  ])
+
+  return (
+    <div className="flex h-full flex-col space-y-6 p-8">
+      <AdminUsersView
+        users={result.items}
+        roleOptions={roleOptions}
+        page={result.page}
+        pageSize={result.pageSize}
+        total={result.total}
+        totalPages={result.totalPages}
+        search={search}
+        roleFilter={role}
+      />
+    </div>
+  )
+}