feat(task1): restructure directories for turborepo monorepo

- Move backend/ to apps/server/ via git mv
- Move frontend/ to apps/admin/ via git mv
- Create packages/typescript-config/ with base, nestjs, and react-vite presets

apps/server/src/entities/classroom-rental.entity.ts

@@ -0,0 +1,58 @@
+import { Entity, PrimaryGeneratedColumn, Column, ManyToOne, JoinColumn, CreateDateColumn, UpdateDateColumn, Index } from 'typeorm';
+import { Classroom } from './classroom.entity';
+import { Tenant } from './tenant.entity';
+
+@Entity('classroom_rentals')
+@Index(['classroomId', 'startDate', 'endDate'])
+export class ClassroomRental {
+  @PrimaryGeneratedColumn()
+  id: number;
+
+  @Column({ name: 'classroom_id' })
+  classroomId: number;
+
+  @ManyToOne(() => Classroom)
+  @JoinColumn({ name: 'classroom_id' })
+  classroom: Classroom;
+
+  @Column({ name: 'tenant_id' })
+  tenantId: number;
+
+  @ManyToOne(() => Tenant)
+  @JoinColumn({ name: 'tenant_id' })
+  tenant: Tenant;
+
+  @Column({ name: 'start_date', type: 'date' })
+  startDate: string;
+
+  @Column({ name: 'end_date', type: 'date' })
+  endDate: string;
+
+  // 合同 PDF 相对路径（相对 UPLOAD_DIR），仅存文件名
+  @Column({ name: 'contract_path', length: 255, nullable: true })
+  contractPath: string;
+
+  @Column({ name: 'contract_original_name', length: 255, nullable: true })
+  contractOriginalName: string;
+
+  @Column({ name: 'daily_rate', type: 'decimal', precision: 10, scale: 2, nullable: true })
+  dailyRate: number;
+
+  @Column({ name: 'total_amount', type: 'decimal', precision: 10, scale: 2, nullable: true })
+  totalAmount: number;
+
+  @Column({ type: 'varchar', length: 20, default: 'active' })
+  status: string; // active / ended / cancelled
+
+  @Column({ type: 'text', nullable: true })
+  notes: string;
+
+  @Column({ name: 'created_by', nullable: true })
+  createdBy: number;
+
+  @CreateDateColumn({ name: 'created_at' })
+  createdAt: Date;
+
+  @UpdateDateColumn({ name: 'updated_at' })
+  updatedAt: Date;
+}