fix(pay): preserve order note JSON, shared coupon burn, plate free VIP cashier

- Order_Repository: status note merges into JSON as status_note instead of wiping coupon/topic_pay meta
- Extract aksrt_burn_order_coupon / aksrt_coupon_usage_exists for content + topic
- Money plate follow (incl. VIP free) always opens multi-gateway cashier for 0-order ledger

inc/classes/class-aksrt-order-repository.php

@@ -316,7 +316,17 @@ class AKSRT_Order_Repository {
         }
 
         if (!empty($extra['note'])) {
-            $update_data['note'] = sanitize_textarea_field($extra['note']);
+            // Preserve JSON pay meta (coupon/topic_pay/content_pay/…); stash human text as status_note.
+            $status_note = sanitize_textarea_field((string) $extra['note']);
+            $raw_note = isset($order['note']) && is_string($order['note']) ? $order['note'] : '';
+            $decoded_note = $raw_note !== '' ? json_decode($raw_note, true) : null;
+            if (is_array($decoded_note)) {
+                $decoded_note['status_note'] = $status_note;
+                $merged = wp_json_encode($decoded_note, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
+                $update_data['note'] = is_string($merged) ? $merged : $status_note;
+            } else {
+                $update_data['note'] = $status_note;
+            }
             $format[] = '%s';
         }
 
@@ -331,6 +341,23 @@ class AKSRT_Order_Repository {
                     'payment_method'         => $update_data['payment_method'] ?? ($order['payment_method'] ?? ''),
                     'payment_transaction_id' => $update_data['payment_transaction_id'] ?? ($order['payment_transaction_id'] ?? ''),
                 ]);
+                if (isset($update_data['note'])) {
+                    // Keep pre-update JSON payload for listeners (coupon burn etc.);
+                    // only attach status_note if callers mutated note.
+                    $pre_meta = [];
+                    $pre_raw = isset($order['note']) && is_string($order['note']) ? $order['note'] : '';
+                    if ($pre_raw !== '') {
+                        $pre_decoded = json_decode($pre_raw, true);
+                        if (is_array($pre_decoded)) {
+                            $pre_meta = $pre_decoded;
+                        }
+                    }
+                    if ($pre_meta !== []) {
+                        $paid_order['meta_payload'] = $pre_meta;
+                        // Prefer merged DB note (JSON + status_note) for downstream reads.
+                        $paid_order['note'] = $update_data['note'];
+                    }
+                }
 
                 /**
                  * 订单到账。