feat(forum): P1 topic coupons, P2 plate follow gateway, cash creator revenue

- Topic_Pay: soft/hard coupon validate, payable amount, free-after-discount, paid burn
- Creator_Revenue: settle content/topic/plate_follow cash (type=order), keep shop path
- Plate VIP1/VIP2 meta + resolve_plate_follow_pay_price via aksrt_get_user_vip_level
- New AKSRT_Plate_Follow_Pay REST multi-gateway; remove Credits×100 money bypass
- Frontend: cms-download plate_follow apiKind + forum-governance money cashier bridge

assets/js/forum-governance.js

@@ -690,10 +690,27 @@
     }
 
     function purchasePlateFollow(plateId, button, payHint) {
+        payHint = payHint || {};
+        var modo = String(payHint.modo || 'money');
+
+        // Cash: multi-gateway cashier (no Credits×100 bypass).
+        if (modo === 'money' && !payHint.is_free) {
+            button.disabled = false;
+            if (typeof window.aksrtOpenCashier === 'function') {
+                window.aksrtOpenCashier(plateId, button, '', '', 'plate_follow');
+                return;
+            }
+            var msgCashier = '收银台未加载，请刷新页面后重试';
+            if (typeof window.aksrtToast === 'function') { window.aksrtToast(msgCashier, 'error'); }
+            else { window.alert(msgCashier); }
+            return;
+        }
+
+        // Points / VIP free: keep AJAX purchase path.
         var confirmMsg = '确认付费关注该版块？';
-        if (payHint && payHint.is_free) {
+        if (payHint.is_free) {
             confirmMsg = '确认使用 VIP 免费关注该版块？';
-        } else if (payHint) {
+        } else {
             confirmMsg = '确认支付 ' + formatFollowPayLabel(payHint) + ' 关注该版块？';
         }
         if (!window.confirm(confirmMsg)) {
@@ -712,14 +729,19 @@
             credentials: 'same-origin',
         }).then(function (r) { return r.json(); }).then(function (payload) {
             if (!payload.success) {
-                throw new Error((payload.data && payload.data.message) || '支付失败');
+                var errData = payload.data || {};
+                // Server may redirect money path to cashier.
+                if (errData.require_cashier && typeof window.aksrtOpenCashier === 'function') {
+                    button.disabled = false;
+                    window.aksrtOpenCashier(plateId, button, '', '', 'plate_follow');
+                    return;
+                }
+                throw new Error(errData.message || '支付失败');
             }
             var res = payload.data || {};
             button.setAttribute('data-followed', '1');
             button.classList.add('is-followed');
-            var label = button.querySelector('span') || button;
             if (button.querySelector('i') && button.childNodes.length) {
-                // keep icon, replace trailing text via last text-ish content
                 button.innerHTML = '<i class="fas fa-heart"></i> 已关注';
             } else {
                 button.textContent = '已关注';