refactor(jackson): 重构 Jackson 配置并添加测试

- 简化了 JacksonConfig 类，移除了自定义时间格式配置
- 添加了 JacksonConfigChecker组件，用于检查 Jackson 配置是否正确
- 新增 JacksonTestController，用于测试 LocalDateTime 序列

src/main/resources/application.yml

@@ -24,12 +24,8 @@ spring:
     date-format: yyyy-MM-dd HH:mm:ss
     serialization:
       write-dates-as-timestamps: false
-      write-null-map-values: false
     deserialization:
       fail-on-unknown-properties: false
-      fail-on-null-for-primitives: false
-      accept-empty-string-as-null-object: true
-    default-property-inclusion: non_null
 
   # 连接池配置
   datasource: