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/platform/web.js

@@ -161,6 +161,40 @@
       .then(packCloudResult);
   }
 
+  function syncCloudFileAfterConflict(id) {
+    var oldKey = (typeof window !== 'undefined' && window.openAs && window.openAs.name) ? window.openAs.name : '';
+    return authedFetch('files/' + id, { headers: { Accept: 'application/json' } })
+      .then(function (response) {
+        if (!response.ok) return null;
+        return response.json();
+      })
+      .then(function (payload) {
+        if (!payload || !payload.ok || !payload.data) return null;
+        var d = payload.data;
+        var newKey = typeof window.soonApplyCloudMeta === 'function'
+          ? window.soonApplyCloudMeta(d)
+          : ('soondesign_file:' + d.id + ':v' + d.version);
+        if (oldKey && oldKey !== newKey && typeof window.soonLocalRemove === 'function') {
+          window.soonLocalRemove(oldKey);
+        }
+        if (typeof window.soonRecentOnCloudSave === 'function') {
+          window.soonRecentOnCloudSave({
+            fileKey: newKey,
+            fileId: d.id,
+            name: d.name,
+            version: d.version
+          }, oldKey, null);
+        }
+        if (typeof window !== 'undefined' && window.openAs && newKey) {
+          window.openAs.name = newKey;
+        }
+        if (typeof window.soonToast === 'function') {
+          window.soonToast('文件已在其他端更新，已同步版本，请再次保存', 'warn');
+        }
+        return newKey;
+      });
+  }
+
   function updateCloudFile(id, name, jsonStr, version) {
     if (!requireCloudAuth('保存')) return Promise.reject(new Error('unauthorized'));
     var body = { name: normalizeSoonName(name), json: jsonStr };
@@ -170,7 +204,19 @@
       headers: JSON_HEADERS,
       body: JSON.stringify(body)
     })
-      .then(function (r) { return r.text().then(function (t) { return handleCloudResponse(r, t); }); })
+      .then(function (r) {
+        return r.text().then(function (t) {
+          if (r.status === 409) {
+            return syncCloudFileAfterConflict(id).then(function () {
+              var err = new Error('version_conflict');
+              err.status = 409;
+              err.conflictSynced = true;
+              return Promise.reject(err);
+            });
+          }
+          return handleCloudResponse(r, t);
+        });
+      })
       .then(packCloudResult);
   }