feat(v1): unify API response, validation, exception handling and tests

src/main/java/com/example/demo/dto/UserRequest.java

@@ -0,0 +1,19 @@
+package com.example.demo.dto;
+
+import jakarta.validation.constraints.Email;
+import jakarta.validation.constraints.Max;
+import jakarta.validation.constraints.Min;
+import jakarta.validation.constraints.NotBlank;
+
+public record UserRequest(
+        @NotBlank(message = "姓名不能为空")
+        String name,
+
+        @NotBlank(message = "邮箱不能为空")
+        @Email(message = "邮箱格式不正确")
+        String email,
+
+        @Min(value = 1, message = "年龄最小为 1")
+        @Max(value = 120, message = "年龄最大为 120")
+        Integer age
+) {}