feat(swagger): support dynamic host via EZ_SWAGGER_HOST env var

- Add ServerConfig.SwaggerHost field
- Set docs.SwaggerInfo.Host dynamically at startup
- Update docker-compose, k8s manifests, and .env.example

.env.example

@@ -20,6 +20,10 @@ EZ_SYNC_OUTBOX_INTERVAL_SECONDS=5
 EZ_SYNC_OUTBOX_BATCH_SIZE=200
 EZ_SYNC_OUTBOX_MAX_RETRIES=10
 
+# Swagger UI Host (留空则使用相对路径，适合反向代理部署)
+# 示例: EZ_SWAGGER_HOST=api.example.com 或 EZ_SWAGGER_HOST=localhost:8080
+EZ_SWAGGER_HOST=
+
 # Log DB (docker-compose log-postgres，可选；默认不启用独立日志库)
 LOG_POSTGRES_USER=postgres
 LOG_POSTGRES_PASSWORD=postgres