feat: add JWT authentication

backend/src/domain/dtos/auth/register-user.dto.ts

@@ -0,0 +1,21 @@
+export class RegisterUserDto {
+  private constructor(
+    public readonly name: string,
+    public readonly email: string,
+    public readonly password: string,
+  ) {}
+
+  static create(props: { [key: string]: any }): [string | undefined, RegisterUserDto?] {
+    const { name, email, password } = props;
+
+    if (!name) return ['name is required'];
+    if (!email) return ['email is required'];
+    if (!password) return ['password is required'];
+
+    if (password.length < 6) {
+      return ['password must be at least 6 characters'];
+    }
+
+    return [undefined, new RegisterUserDto(name, email, password)];
+  }
+}