feat(admin-portal): 完成参考项目差距闭环 - 4 批次补齐 + Vitest 测试

差距分析闭环（workline §7-§8）：
- P0：审计子模块 3 页 + 学校组织 7 页
- P1：系统设置 4 Card + 公告管理 + 邀请码管理
- P2：文件管理 + AI 配置
- P6：5 测试文件 / 69 用例全过

共享基础设施：
- permissions +11 权限点 +14 路由
- view-models +20 接口
- i18n +100 key
- graphql-client +25 operation
- fixtures/handlers +15 mock +20 handler

质量：typecheck + lint 零错误，vitest 69/69 通过，arch.db 已更新

apps/admin-portal/src/app/admin/school/departments/page.tsx

@@ -0,0 +1,77 @@
+"use client";
+
+import { type ReactNode, useState } from "react";
+import { useDepartments, useSchools } from "@/hooks/use-school";
+import {
+  PaperCard,
+  Select,
+  LoadingState,
+  ErrorState,
+  EmptyState,
+  Table,
+  TableRow,
+  TableCell,
+} from "@/components/ui";
+import { t } from "@/lib/i18n";
+
+export default function DepartmentsPage(): ReactNode {
+  const [schoolId, setSchoolId] = useState<string>("");
+  const { data: schools, loading: schoolsLoading } = useSchools();
+  const { data, loading, error } = useDepartments(schoolId || undefined);
+
+  return (
+    <>
+      <PaperCard className="p-4 mb-4">
+        <Select
+          value={schoolId}
+          onChange={(e) => setSchoolId(e.target.value)}
+          disabled={schoolsLoading}
+        >
+          <option value="">
+            {t("admin.common.all")}
+            {t("admin.common.school")}
+          </option>
+          {schools.map((s) => (
+            <option key={s.id} value={s.id}>
+              {s.name}
+            </option>
+          ))}
+        </Select>
+      </PaperCard>
+
+      <PaperCard className="p-4">
+        {loading && <LoadingState />}
+        {error && <ErrorState message={error.message} />}
+        {!loading && !error && (
+          <>
+            {data.length === 0 ? (
+              <EmptyState message={t("admin.common.empty")} />
+            ) : (
+              <Table
+                headers={[
+                  "部门",
+                  t("admin.common.school"),
+                  t("admin.school.leader"),
+                  t("admin.school.memberCount"),
+                  t("admin.school.subject"),
+                ]}
+              >
+                {data.map((dept) => (
+                  <TableRow key={dept.id}>
+                    <TableCell style={{ fontWeight: 500 }}>
+                      {dept.name}
+                    </TableCell>
+                    <TableCell>{dept.schoolName}</TableCell>
+                    <TableCell>{dept.leaderName ?? "—"}</TableCell>
+                    <TableCell>{dept.memberCount}</TableCell>
+                    <TableCell>{dept.subject ?? "—"}</TableCell>
+                  </TableRow>
+                ))}
+              </Table>
+            )}
+          </>
+        )}
+      </PaperCard>
+    </>
+  );
+}