feat(offer): 抽取 copyToClipboard 兼容助手，支持非 https/localhost 剪贴板回退 (execCommand)

vue-app/src/components/offer/OfferFlow.vue

@@ -195,25 +195,46 @@ const reopenOffer = () => {
   }
 }
 
-const copyMaterials = async () => {
-  const text = materials.value?.items.map((item) => `${item.label}：${item.value}`).join('\n') || ''
+// 剪贴板写入需兼容非 https/localhost 等不支持 Clipboard API 的环境
+const copyToClipboard = async (text = '') => {
+  if (!text) return false
+  if (navigator.clipboard?.writeText) {
     try {
       await navigator.clipboard.writeText(text)
-    showToast('审批材料已复制')
+      return true
     } catch {
-    showToast('复制失败', 'error')
+      // 权限不足或调用失败，回退到 execCommand
     }
+  }
+  try {
+    const textarea = document.createElement('textarea')
+    textarea.value = text
+    textarea.style.position = 'fixed'
+    textarea.style.opacity = '0'
+    document.body.appendChild(textarea)
+    textarea.focus()
+    textarea.select()
+    const ok = document.execCommand('copy')
+    document.body.removeChild(textarea)
+    return ok
+  } catch {
+    return false
+  }
+}
+
+const copyMaterials = async () => {
+  const text = materials.value?.items.map((item) => `${item.label}：${item.value}`).join('\n') || ''
+  const ok = await copyToClipboard(text)
+  if (ok) showToast('审批材料已复制')
+  else showToast('复制失败', 'error')
 }
 
 const copyMail = async () => {
   const text = offer.value?.mailDraft || ''
   if (!text) return
-  try {
-    await navigator.clipboard.writeText(text)
-    showToast('邮件草稿已复制')
-  } catch {
-    showToast('复制失败', 'error')
-  }
+  const ok = await copyToClipboard(text)
+  if (ok) showToast('邮件草稿已复制')
+  else showToast('复制失败', 'error')
 }
 
 // 当前唯一的「下一步」主操作：放进工作流面板，让页面只有一处突出主 CTA，