feat(news): 支持新闻中心多站点隔离功能

新增站点编码配置，支持新闻分类与文章按站点隔离。主要变更包括：
- 数据库表增加 site_code 字段及索引
- 后台管理界面支持按站点筛选
- 前台接口支持通过查询参数或请求头指定站点
- 新增站点配置与解析逻辑

server/target/maven-status/maven-compiler-plugin/compile/default-compile/inputFiles.lst

@@ -4,9 +4,12 @@ D:\DeXun_workspace\projects\wuhan-saga-official-website\server\src\main\java\com
 D:\DeXun_workspace\projects\wuhan-saga-official-website\server\src\main\java\com\wuhansaga\server\common\PageResult.java
 D:\DeXun_workspace\projects\wuhan-saga-official-website\server\src\main\java\com\wuhansaga\server\common\R.java
 D:\DeXun_workspace\projects\wuhan-saga-official-website\server\src\main\java\com\wuhansaga\server\config\OpenApiConfig.java
+D:\DeXun_workspace\projects\wuhan-saga-official-website\server\src\main\java\com\wuhansaga\server\config\PortalSiteProperties.java
+D:\DeXun_workspace\projects\wuhan-saga-official-website\server\src\main\java\com\wuhansaga\server\config\PortalSiteResolver.java
 D:\DeXun_workspace\projects\wuhan-saga-official-website\server\src\main\java\com\wuhansaga\server\config\RedisConfig.java
 D:\DeXun_workspace\projects\wuhan-saga-official-website\server\src\main\java\com\wuhansaga\server\config\SaTokenConfig.java
 D:\DeXun_workspace\projects\wuhan-saga-official-website\server\src\main\java\com\wuhansaga\server\config\WebMvcConfig.java
+D:\DeXun_workspace\projects\wuhan-saga-official-website\server\src\main\java\com\wuhansaga\server\constant\SiteCodes.java
 D:\DeXun_workspace\projects\wuhan-saga-official-website\server\src\main\java\com\wuhansaga\server\controller\admin\AdminAboutController.java
 D:\DeXun_workspace\projects\wuhan-saga-official-website\server\src\main\java\com\wuhansaga\server\controller\admin\AdminAuthController.java
 D:\DeXun_workspace\projects\wuhan-saga-official-website\server\src\main\java\com\wuhansaga\server\controller\admin\AdminBannerController.java
@@ -58,6 +61,7 @@ D:\DeXun_workspace\projects\wuhan-saga-official-website\server\src\main\java\com
 D:\DeXun_workspace\projects\wuhan-saga-official-website\server\src\main\java\com\wuhansaga\server\mapper\NewsCategoryMapper.java
 D:\DeXun_workspace\projects\wuhan-saga-official-website\server\src\main\java\com\wuhansaga\server\mapper\NewsMapper.java
 D:\DeXun_workspace\projects\wuhan-saga-official-website\server\src\main\java\com\wuhansaga\server\mapper\ProductCategoryMapper.java
+D:\DeXun_workspace\projects\wuhan-saga-official-website\server\src\main\java\com\wuhansaga\server\mapper\ProductLineEquipmentMapper.java
 D:\DeXun_workspace\projects\wuhan-saga-official-website\server\src\main\java\com\wuhansaga\server\mapper\ProductLineMapper.java
 D:\DeXun_workspace\projects\wuhan-saga-official-website\server\src\main\java\com\wuhansaga\server\mapper\ProductMediaMapper.java
 D:\DeXun_workspace\projects\wuhan-saga-official-website\server\src\main\java\com\wuhansaga\server\mapper\SingleEquipmentMapper.java