feat: 交付官方 Docker 运行时，外观改背景图并下线自定义 CSS/JS

站点/后台分轨背景与用户列表排序一并落地；生产 CORS 改走 SITE_URL，健康检查带版本号。

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/cmd/jiang13/main.go

@@ -8,6 +8,7 @@ import (
 	"github.com/freefire/jiang13-bbs/model"
 	"github.com/freefire/jiang13-bbs/router"
 	"github.com/freefire/jiang13-bbs/service"
+	"github.com/freefire/jiang13-bbs/version"
 )
 
 func main() {
@@ -33,7 +34,7 @@ func main() {
 	}
 
 	addr := fmt.Sprintf(":%d", cfg.Port)
-	log.Printf("[jiang13-bbs] 服务启动于 %s (dev=%v workPath=%s dataDir=%s)", addr, cfg.DevMode, cfg.WorkPath, cfg.DataDir)
+	log.Printf("[jiang13-bbs] 服务启动于 %s (version=%s commit=%s dev=%v workPath=%s dataDir=%s)", addr, version.Version, version.Commit, cfg.DevMode, cfg.WorkPath, cfg.DataDir)
 	if err := r.Run(addr); err != nil {
 		log.Fatalf("服务启动失败: %v", err)
 	}