fix(pay): 待支付浮窗无刷新同步

- modal-cache 失效时广播 aksrt:cache:invalidated
- 新增 GET /orders/wait-pay-float 返回浮窗片段
- wait-pay-float.js 监听 orders 标签失效并替换/移除浮窗、重启倒计时
- VIP/充值/下载待支付分支触发 orders 失效

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

assets/js/vip-purchase-coordinator.js

@@ -375,6 +375,7 @@
         return response;
       }
       if (data.redirect && (data.payment_url || data.qr_content)) {
+        invalidate(["orders"]);
         callback(options, "onPending", data);
         if (!data.order_number) {
           var missing = { ok: false, status: 500, json: { message: "订单号缺失" } };