fix: 离线证到期重签空邮箱撞唯一索引

复用 customer_id/同名客户，禁止重复插入空 email；重签前端带回原客户。

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/views/OfflineLicenses.vue

@@ -135,7 +135,7 @@ const issueVisible = ref(false)
 const issuing = ref(false)
 const formRef = ref(null)
 const form = reactive({
-  device_id: '', email: '', customer_name: '', product_code: 'opsxshell',
+  device_id: '', email: '', customer_name: '', customer_id: 0, product_code: 'opsxshell',
   plan_type: 'yearly', duration_days: 365, notes: '',
 })
 const result = ref(null)
@@ -167,7 +167,7 @@ async function loadData() {
 
 function openIssue() {
   Object.assign(form, {
-    device_id: '', email: '', customer_name: '', product_code: 'opsxshell',
+    device_id: '', email: '', customer_name: '', customer_id: 0, product_code: 'opsxshell',
     plan_type: 'yearly', duration_days: 365, notes: '',
   })
   result.value = null
@@ -177,8 +177,9 @@ function openIssue() {
 function reissue(row) {
   Object.assign(form, {
     device_id: row.device_id || '',
-    email: '',
+    email: row.customer_email || '',
     customer_name: row.customer_name || '',
+    customer_id: row.customer_id || 0,
     product_code: 'opsxshell',
     plan_type: row.is_trial ? 'trial' : 'yearly',
     duration_days: row.is_trial ? 180 : 365,
@@ -193,7 +194,7 @@ async function submitIssue() {
     if (!valid) return
     issuing.value = true
     try {
-      const res = await issueOfflineLicense({
+      const payload = {
         device_id: form.device_id.trim(),
         email: form.email.trim() || undefined,
         customer_name: form.customer_name.trim() || undefined,
@@ -201,7 +202,11 @@ async function submitIssue() {
         duration_days: form.duration_days,
         notes: form.notes,
         product_code: form.product_code.trim() || 'opsxshell',
-      })
+      }
+      if (form.customer_id > 0) {
+        payload.customer_id = form.customer_id
+      }
+      const res = await issueOfflineLicense(payload)
       result.value = res.data
       loadData()
       ElMessage.success('已签发（请复制序列号；列表仅显示短码）')