feat(admin): remove all department/campus scoping from frontend

- Delete CampusSwitcher component and useCampus hook
- Delete Departments page and its route
- Remove campus header interceptor from API client
- Remove departmentId from Class interfaces
- Remove campusLocation from student profile
- Remove department permissions from test fixtures
- Remove currentCampusId from test cleanup

TypeScript compiles clean.

apps/admin/src/components/CampusSwitcher.tsx

@@ -1,36 +0,0 @@
-import React from 'react';
-import { Select, Typography } from 'antd';
-import { EnvironmentOutlined } from '@ant-design/icons';
-import { useCampus } from '../hooks/useCampus';
-
-const CampusSwitcher: React.FC = () => {
-  const { campuses, currentId, switchCampus, loading } = useCampus();
-
-  if (campuses.length <= 1) {
-    return (
-      <Typography.Text style={{ color: '#fff', marginRight: 24 }}>
-        <EnvironmentOutlined style={{ marginRight: 4 }} />
-        {campuses[0]?.name || '主校区'}
-      </Typography.Text>
-    );
-  }
-
-  const options = [
-    ...campuses.map((c) => ({ value: String(c.id), label: c.name })),
-    { value: '', label: '全部校区' },
-  ];
-
-  return (
-    <Select
-      value={currentId || undefined}
-      onChange={switchCampus}
-      options={options}
-      loading={loading}
-      style={{ minWidth: 140, marginRight: 24 }}
-      variant="borderless"
-      popupMatchSelectWidth={false}
-    />
-  );
-};
-
-export default CampusSwitcher;

apps/admin/src/components/StudentProfileContent/index.tsx

@@ -53,7 +53,6 @@ interface ProfileData {
   targetMajor?: string;
   subjectDirection?: string;
   grade?: string;
-  campusLocation?: string;
   profileDate?: string;
   notes?: string;
 }
@@ -220,7 +219,6 @@ const ProfileTab: React.FC<{ data: ProfileData | null; studentId: number; onRefr
           targetMajor: data?.targetMajor ?? undefined,
           subjectDirection: data?.subjectDirection ?? undefined,
           grade: data?.grade ?? undefined,
-          campusLocation: data?.campusLocation ?? undefined,
           profileDate: data?.profileDate ? dayjs(data.profileDate) : undefined,
           notes: data?.notes ?? undefined,
         }}
@@ -238,9 +236,6 @@ const ProfileTab: React.FC<{ data: ProfileData | null; studentId: number; onRefr
         <Form.Item name="grade" label="年级">
           <Input placeholder="如：高三" />
         </Form.Item>
-        <Form.Item name="campusLocation" label="校区">
-          <Input placeholder="请输入校区" />
-        </Form.Item>
         <Form.Item name="profileDate" label="建档日期">
           <DatePicker style={{ width: '100%' }} />
         </Form.Item>
@@ -903,9 +898,6 @@ const StudentProfileContent: React.FC<StudentProfileContentProps> = ({
         {profile?.subjectDirection && (
           <Descriptions.Item label="选科方向">{profile.subjectDirection}</Descriptions.Item>
         )}
-        {profile?.campusLocation && (
-          <Descriptions.Item label="校区">{profile.campusLocation}</Descriptions.Item>
-        )}
       </Descriptions>
 
       <Tabs