fix: add onDelete cascade for User FK in class_teacher and students entities

apps/server/src/entities/class-teacher.entity.ts

@@ -33,7 +33,7 @@ export class ClassTeacher {
   @Column({ name: 'user_id', type: 'integer' })
   userId: number;
 
-  @ManyToOne(() => User)
+  @ManyToOne(() => User, { onDelete: 'CASCADE' })
   @JoinColumn({ name: 'user_id' })
   user: User;
 

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

@@ -65,7 +65,7 @@ export class Student {
   @Column({ name: 'user_id', type: 'integer', nullable: true, unique: true })
   userId: number;
 
-  @OneToOne(() => User, { nullable: true })
+  @OneToOne(() => User, { nullable: true, onDelete: 'SET NULL' })
   @JoinColumn({ name: 'user_id' })
   user: User;