style(service): modify package name "service" to "sys"

web/handler.go

@@ -45,7 +45,7 @@ func ServeStatic(w http.ResponseWriter, r *http.Request) {
 		}
 
 		setContentType(w, path.Ext(filePath))
-		http.ServeContent(w, r, filePath, stat.ModTime(), f.(http.File))
+		http.ServeContent(w, r, filePath, stat.ModTime(), f)
 		return
 	}