完善下单逻辑及其ui展示，修复支付倒计时显示错误bug

pages/mall/consumer/home-service/apply.uvue

@@ -149,6 +149,13 @@ async function loadData() {
 	bookingDays.value = getBookingDayOptions()
 	bookingSlots.value = getBookingTimeSlots()
 	services.value = await fetchHomeServiceCatalog()
+	if (services.value.length > 0) {
+		selectService(services.value[0].id, services.value[0].name)
+		return
+	}
+	selectedServiceId.value = ''
+	form.serviceId = ''
+	form.serviceName = ''
 }
 
 function selectService(serviceId: string, serviceName: string) {
@@ -192,6 +199,10 @@ function selectSlot(slotId: string, available: boolean) {
 }
 
 async function submitApplication() {
+	if (form.serviceId == '' || form.serviceName == '') {
+		uni.showToast({ title: '当前没有可预约的服务项目', icon: 'none' })
+		return
+	}
 	if (form.applicantName == '' || form.elderName == '' || form.phone == '' || form.address == '' || form.preferredTime == '') {
 		uni.showToast({ title: '请补全申请信息', icon: 'none' })
 		return
@@ -200,6 +211,10 @@ async function submitApplication() {
 	const parsedAge = parseInt(ageText.value)
 	form.age = isNaN(parsedAge) ? 0 : parsedAge
 	const created = await createHomeServiceApplication(form)
+	if (created == null) {
+		uni.showToast({ title: '申请提交失败，请检查登录和预约信息', icon: 'none' })
+		return
+	}
 	uni.showToast({ title: '申请已提交', icon: 'success' })
 	uni.navigateTo({ url: '/pages/mall/consumer/home-service/order-detail?id=' + created.id })
 }