change role id to string and set default value

backend/src/entities/role.entity.ts

@@ -8,7 +8,7 @@ import{
 @Entity('role')
 export class RoleEntity extends BaseEntity{
     @PrimaryGeneratedColumn('uuid')
-    id: number;
+    id: string;
 
     @Column({ nullable: false})
     role_name: string;

backend/src/entities/user.entity.ts

@@ -34,9 +34,8 @@ export class UserEntity extends BaseEntity {
   @Column({ nullable: true, unique: true })
   email: string;
 
-  @IsOptional()
-  @Column({ nullable: true })
-  role_id: number;
+  @Column({ default: 'f3750930-48ab-4c30-8681-d50e68e2bda7' })
+  role_id: string;
   
   @Column()
   hash_password: string;