feat: add user submission functionality

src/modules/questions/entities/question.entity.ts

@@ -36,6 +36,7 @@ export class Question {
   content!: string;
 
   @Column({ type: 'int', nullable: false })
+  @Index()
   order!: number;
 
   @Column({ type: 'int', default: 1 })
@@ -51,7 +52,7 @@ export class Question {
   metadata!: QuestionMetadata;
 
   @OneToMany(() => Choice, (choice) => choice.question)
-  choices?: Array<Choice>;
+  choices!: Array<Choice>;
 
   @CreateDateColumn()
   createdAt!: Date;