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/addMember/addMember.ts

@@ -299,6 +299,9 @@ Page({
 			'form.height': String(member.height),
 			'form.weight': String(member.weight),
 		})
+		if (member.name.trim() && this.isIdCardValid(member.idCard)) {
+			this.fetchUserInfoByIdCard(member.name.trim(), member.idCard)
+		}
 	},
 
 	/** 确认弹框 - 确认 */