fix(user-center): complete certification and order flows

Fix modal scroll ownership and certification modal styling, store evidence as Media Library attachments, reconcile missed provider callbacks, validate currencies, and complete digital fulfillment only after durable entitlement delivery.

assets/js/routes/user-center.js

@@ -262,10 +262,16 @@
 			}
 			if (message) message.textContent = '';
 			fetch(ajaxUrl, { method: 'POST', body: new FormData(form), credentials: 'same-origin' })
-				.then(function(response) { return response.json(); })
 				.then(function(response) {
-					if (!response || response.error) throw new Error((response && response.msg) || '提交失败');
-					showToast(response.msg || '提交成功');
+					return response.json().then(function(payload) {
+						if (!response.ok || !payload || !payload.success) {
+							throw new Error((payload && payload.data && payload.data.message) || '提交失败');
+						}
+						return payload.data || {};
+					});
+				})
+				.then(function(data) {
+					showToast(data.message || '提交成功');
 					window.setTimeout(function() { window.location.assign(tabUrls.auth || '?tab=auth'); }, 500);
 				})
 				.catch(function(error) {