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/personal-expense.entity.ts

@@ -0,0 +1,36 @@
+import { Entity, PrimaryGeneratedColumn, Column, CreateDateColumn, ManyToOne, JoinColumn } from 'typeorm';
+import { Student } from './student.entity';
+
+@Entity('personal_expenses')
+export class PersonalExpense {
+  @PrimaryGeneratedColumn()
+  id: number;
+
+  @Column({ name: 'student_id' })
+  studentId: number;
+
+  @Column({ name: 'room_id', nullable: true })
+  roomId: number;
+
+  @Column({ name: 'expense_type', type: 'varchar', length: 20 })
+  expenseType: string;
+
+  @Column({ type: 'decimal', precision: 10, scale: 2 })
+  amount: number;
+
+  @Column({ name: 'expense_date', type: 'date' })
+  expenseDate: string;
+
+  @Column({ type: 'text', nullable: true })
+  description: string;
+
+  @Column({ name: 'recorded_by', nullable: true })
+  recordedBy: number;
+
+  @CreateDateColumn({ name: 'created_at' })
+  createdAt: Date;
+
+  @ManyToOne(() => Student, (s) => s.personalExpenses)
+  @JoinColumn({ name: 'student_id' })
+  student: Student;
+}