feat(addMember): 选择已有成员补服务端校验；表单加scroll-view；上限10人限制

- onSelectMember 选中后调用 fetchUserInfoByIdCard 走服务端校验
- 表单区域包裹 scroll-view，适配小屏滚动
- equipmentMember 添加按钮超10人弹 toast 提示

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

miniprogram/pages/equipmentMember/equipmentMember.ts

@@ -292,6 +292,10 @@ Page({
     /** 添加成员：未连接态禁用 */
     onTapAddMember() {
         if (!this.data.connected) return
+        if (this.data.memberList.length >= 10) {
+            wx.showToast({ title: '超过最大用户限制', icon: 'none' })
+            return
+        }
         wx.navigateTo({ url: '/pages/addMember/addMember' })
     },
 })