全局重命名：kefu_sys / kefu-sys 改为 kefu_cloud / kefu-cloud

- Go module 与全部 import 路径
- 数据库默认库名、Docker 服务/卷命名与部署文档

server/internal/handler/upload.go

@@ -9,10 +9,10 @@ import (
 	"strings"
 
 	"github.com/gin-gonic/gin"
-	"kefu-sys/server/internal/config"
-	"kefu-sys/server/internal/media"
-	"kefu-sys/server/internal/middleware"
-	"kefu-sys/server/internal/storage"
+	"kefu-cloud/server/internal/config"
+	"kefu-cloud/server/internal/media"
+	"kefu-cloud/server/internal/middleware"
+	"kefu-cloud/server/internal/storage"
 )
 
 type UploadHandler struct {