fix(mp): 注册 MyBatis-Plus 分页拦截器，修复 page() 返回 total=0

- 新增 MybatisPlusConfig 注册 PaginationInnerInterceptor
- 修复分页查询只填充 records、total/pages 恒为 0 的问题

src/main/java/com/freedom/admin/config/MybatisPlusConfig.java

@@ -0,0 +1,26 @@
+package com.freedom.admin.config;
+
+import com.baomidou.mybatisplus.annotation.DbType;
+import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
+import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+/**
+ * MyBatis-Plus 分页插件配置
+ *
+ * @author zhangjiaxun
+ * @description 注册分页拦截器后，Service.page() 才会执行 count 并返回正确的 total/pages，
+ *              否则仅填充 records 而 total 恒为 0
+ */
+@Configuration
+public class MybatisPlusConfig {
+
+    @Bean
+    public MybatisPlusInterceptor mybatisPlusInterceptor() {
+        MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
+        interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
+        return interceptor;
+    }
+
+}