fix(xiaomi): 增加 payload 传递和 extra.notify_effect=1 确保点击打开应用

- 推送请求携带 payload，SDK 点击通知后可从中解析 URL
- 固定设置 extra.notify_effect=1 确保 HyperOS 点击通知时打开应用

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

push-service/src/main/java/com/xuqm/push/service/provider/XiaomiPushProvider.java

@@ -71,7 +71,11 @@ public class XiaomiPushProvider implements PushProvider {
                 .append("&title=").append(URLEncoder.encode(title, StandardCharsets.UTF_8))
                 .append("&description=").append(URLEncoder.encode(body, StandardCharsets.UTF_8))
                 .append("&restricted_package_name=").append(URLEncoder.encode(packageName, StandardCharsets.UTF_8))
-                .append("&extra.notify_foreground=1");
+                .append("&extra.notify_foreground=1")
+                .append("&extra.notify_effect=1");
+            if (payload != null && !payload.isBlank()) {
+                form.append("&payload=").append(URLEncoder.encode(payload, StandardCharsets.UTF_8));
+            }
             Integer notifyType = options != null ? options.notifyType() : null;
             form.append("&notify_type=").append(notifyType == null ? 1 : Math.max(notifyType, 0));
             if (!channelId.isBlank()) {