docs(spring-boot): align examples with documented conventions

Two consistency cleanups:

- Drop redundant column aliases in the MyBatis Mapper example; map-underscore-to-camel-case is already enabled in application.yml, so the explicit aliases are noise.
- Re-nest the request/response directories under a top-level domain/ package in the end-to-end example to match the project layout shown earlier in the skill. The transfer-objects section already refers to com.example.app.domain.request.* and com.example.app.domain.response.* implicitly via the layout tree.

Also drops the now-orphaned 阿里巴巴《Java 开发手册》 line from Authoritative References, since the rest of the skill no longer leans on it for terminology.

spring-boot/SKILL.md

@@ -507,14 +507,14 @@ A protected no-arg constructor is required by JPA. Static factories (`fromReques
 public interface UserMapper {
 
     @Select("""
-        SELECT id, email, display_name AS displayName, status, created_at AS createdAt
+        SELECT id, email, display_name, status, created_at
         FROM users
         WHERE id = #{id}
         """)
     Optional<UserEntity> findById(Long id);
 
     @Select("""
-        SELECT id, email, display_name AS displayName, status, created_at AS createdAt
+        SELECT id, email, display_name, status, created_at
         FROM users
         <where>
           <if test="email != null">AND email LIKE CONCAT('%', #{email}, '%')</if>
@@ -780,11 +780,12 @@ com.example.app/
 │   └── UserMapper.java                      (MyBatis, when needed)
 ├── entity/
 │   └── UserEntity.java
-├── request/
-│   ├── CreateUserRequest.java
-│   ├── UpdateUserRequest.java
-│   └── UserSearchCriteria.java
-├── response/
+├── domain/
+│   ├── request/
+│   │   ├── CreateUserRequest.java
+│   │   ├── UpdateUserRequest.java
+│   │   └── UserSearchCriteria.java
+│   └── response/
 │       └── UserResponse.java
 └── enums/
     └── UserStatus.java
@@ -822,4 +823,3 @@ public class App {
 - Spring Data JPA Reference
 - Jakarta Bean Validation 3.0
 - springdoc-openapi 2.x
-- 阿里巴巴《Java 开发手册》(层结构、Manager/Client 命名来源)