优化支付宝支付流程与 Web 端体验

- 支付宝新窗口跳转，轮询与手动刷新增加加载反馈
- 支付回跳先校验订单状态，避免未付款误报成功
- 门户登录回调统一，云文件打开加载与版本冲突同步
- 精简本地 start.bat 与 README 说明

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

frontend-web/js/design2/output.js

@@ -1517,7 +1517,9 @@ window.openFile = function open(file, jAlready) {
         return;
     }
     if (window.platformBridge && window.platformBridge.readJsonFile) {
+        if (typeof window.soonShowOpenFileLoading === 'function') window.soonShowOpenFileLoading();
         return window.platformBridge.readJsonFile(file).then(function(j) {
+            if (typeof window.soonHideOpenFileLoading === 'function') window.soonHideOpenFileLoading();
             if (j) {
                 doOpenWithJson(j);
                 openAs.name = file;
@@ -1526,6 +1528,7 @@ window.openFile = function open(file, jAlready) {
             }
         }).catch(function () {
             if (typeof window.soonReportOpenLoadError === 'function') window.soonReportOpenLoadError('模板/文件加载失败');
+            else if (typeof window.soonHideOpenFileLoading === 'function') window.soonHideOpenFileLoading();
         });
     }
     try {