feat: add department_id to all business entities

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

@@ -1,6 +1,7 @@
-import { Entity, PrimaryGeneratedColumn, Column, CreateDateColumn, OneToMany } from 'typeorm';
+import { Entity, PrimaryGeneratedColumn, Column, CreateDateColumn, OneToMany, ManyToOne, JoinColumn } from 'typeorm';
 import { Occupancy } from './occupancy.entity';
 import { RoomExpense } from './room-expense.entity';
+import { Department } from './department.entity';
 
 @Entity('rooms')
 export class Room {
@@ -42,4 +43,11 @@ export class Room {
 
   @OneToMany(() => RoomExpense, (e) => e.room)
   roomExpenses: RoomExpense[];
+
+  @Column({ name: 'department_id', type: 'integer', nullable: true })
+  departmentId: number;
+
+  @ManyToOne(() => Department, { nullable: true })
+  @JoinColumn({ name: 'department_id' })
+  department: Department;
 }