refactor(server): remove Department/UserDepartment entities, CampusScope, and departmentId from all entities

- Delete department.entity.ts, user-department.entity.ts
- Remove Department/UserDepartment from entities/index.ts
- Remove departmentId column from 18 entities (AttendanceRecord, ArchiveAttachment, Bill, ClassSchedule, Classroom, ClassroomRental, Deposit, DepositInstallment, ExamScore, LearningRecord, Occupancy, PersonalExpense, ResultArchive, Room, RoomExpense, Student, StudentEnrollment, StudentProfile, StudentReport)
- Remove departments/ module entirely
- Delete campus-scope.ts, campus-scope.middleware.ts (request-utils.ts kept — it's just IP extraction)
- Simplify common.module.ts to empty module
- Remove CampusScopeMiddleware from app.module.ts
- Remove all CampusScope injections and filter calls across all services
- Remove departmentId from all DTOs and controllers
- Simplify dingtalk/wecom sync to only sync users (no dept table)
- Update seed module to remove department seeding
- Clean frontend compilation

apps/server/src/entities/occupancy.entity.ts

@@ -11,7 +11,6 @@ import { Room } from './room.entity';
 import { Tenant } from './tenant.entity';
 import { Bed } from './bed.entity';
 import { Locker } from './locker.entity';
-import { Department } from './department.entity';
 
 @Entity('occupancies')
 export class Occupancy {
@@ -77,10 +76,4 @@ export class Occupancy {
   @JoinColumn({ name: 'room_id' })
   room: Room;
 
-  @Column({ name: 'department_id', type: 'integer', nullable: true })
-  departmentId: number;
-
-  @ManyToOne(() => Department, { nullable: true })
-  @JoinColumn({ name: 'department_id' })
-  department: Department;
 }