feat: add exam score management

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

@@ -0,0 +1,49 @@
+import {
+  Column,
+  CreateDateColumn,
+  Entity,
+  JoinColumn,
+  ManyToOne,
+  OneToMany,
+  PrimaryGeneratedColumn,
+  UpdateDateColumn,
+} from 'typeorm';
+import { Class } from './class.entity';
+import { ExamScore } from './exam-score.entity';
+
+@Entity('exams')
+export class Exam {
+  @PrimaryGeneratedColumn()
+  id: number;
+
+  @Column({ name: 'exam_type', length: 50 })
+  examType: string;
+
+  @Column({ name: 'exam_name', length: 100 })
+  examName: string;
+
+  @Column({ length: 50 })
+  subject: string;
+
+  @Column({ name: 'exam_date', type: 'date' })
+  examDate: string;
+
+  @Column({ name: 'class_id', type: 'integer' })
+  classId: number;
+
+  @ManyToOne(() => Class)
+  @JoinColumn({ name: 'class_id' })
+  class: Class;
+
+  @OneToMany(() => ExamScore, (score) => score.exam)
+  scores: ExamScore[];
+
+  @Column({ type: 'varchar', length: 20, default: 'active' })
+  status: 'active' | 'archived';
+
+  @CreateDateColumn({ name: 'created_at' })
+  createdAt: Date;
+
+  @UpdateDateColumn({ name: 'updated_at' })
+  updatedAt: Date;
+}