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/deposit.entity.ts

@@ -0,0 +1,46 @@
+import { Entity, PrimaryGeneratedColumn, Column, CreateDateColumn, ManyToOne, JoinColumn } from 'typeorm';
+import { Student } from './student.entity';
+
+@Entity('deposits')
+export class Deposit {
+  @PrimaryGeneratedColumn()
+  id: number;
+
+  @Column({ name: 'student_id' })
+  studentId: number;
+
+  @Column({ type: 'decimal', precision: 10, scale: 2, default: 500 })
+  amount: number;
+
+  // paid: 已缴 | refunded: 已退 | deducted: 已扣除（部分或全部）
+  @Column({ type: 'varchar', length: 20, default: 'paid' })
+  status: string;
+
+  @Column({ name: 'paid_date', type: 'date' })
+  paidDate: string;
+
+  @Column({ name: 'refund_date', type: 'date', nullable: true })
+  refundDate: string;
+
+  @Column({ name: 'refund_amount', type: 'decimal', precision: 10, scale: 2, nullable: true })
+  refundAmount: number;
+
+  @Column({ name: 'deduction_amount', type: 'decimal', precision: 10, scale: 2, default: 0 })
+  deductionAmount: number;
+
+  @Column({ name: 'deduction_reason', type: 'text', nullable: true })
+  deductionReason: string;
+
+  @Column({ type: 'text', nullable: true })
+  notes: string;
+
+  @Column({ name: 'recorded_by', nullable: true })
+  recordedBy: number;
+
+  @CreateDateColumn({ name: 'created_at' })
+  createdAt: Date;
+
+  @ManyToOne(() => Student, { eager: true })
+  @JoinColumn({ name: 'student_id' })
+  student: Student;
+}