feat: Add Cross-Domain Job Fair and Alliance City Management

- Implemented AppOutdoorFairController for outdoor job fair public H5 interfaces.
- Created CrossCityAllianceController for managing cross-domain alliance cities.
- Added CrossCityAlliance domain model and corresponding service and mapper.
- Developed CrossDomainJobVO for aggregating job data across job fairs.
- Created SQL scripts for initializing the cross-city alliance table and modifying the public job fair schema.
- Added migration script for backing up and restoring the HighGo database schema.

sql/public_job_fair_cross_domain_cities.sql

@@ -0,0 +1,7 @@
+-- 公共招聘会：新增「跨域联盟城市」列，存逗号分隔的城市名称。
+-- 依赖：shz.public_job_fair 已存在；shz.cms_cross_city_alliance 提供城市数据。
+
+ALTER TABLE public_job_fair
+    ADD COLUMN IF NOT EXISTS cross_domain_cities VARCHAR(500);
+
+COMMENT ON COLUMN public_job_fair.cross_domain_cities IS '跨域联盟城市（逗号分隔的城市名称）';