feat: 删除JSP视图层，完善评价和通知系统，新增拼团模块

- 删除所有 JSP 页面（20个文件），前端完全迁移至 Vue 3 SPA
- 完善评价系统：ReviewDialog 组件、用户评价历史页、评价状态检查API
- 新增通知系统：Notification 实体/仓库/服务/控制器，NotificationCenter 接入真实API
- 新增拼团模块：GroupBuying 全套后端和前端页面
- 修复 review check API 参数双重包装导致请求格式错误
- 修复通知 API 路径缺少 /api 前缀和响应格式处理
- MessageListenerService 集成 NotificationService 创建持久化通知

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

flash-sale-frontend/src/pages/admin/flashsales.vue

@@ -128,10 +128,22 @@
           </el-col>
         </el-row>
         <el-form-item label="开始时间" prop="startTime">
-          <el-date-picker v-model="form.startTime" type="datetime" value-format="YYYY-MM-DD HH:mm:ss" class="w-full" />
+          <el-date-picker
+            v-model="form.startTime"
+            type="datetime"
+            value-format="YYYY-MM-DD HH:mm:ss"
+            :disabled-date="disablePastDate"
+            class="w-full"
+          />
         </el-form-item>
         <el-form-item label="结束时间" prop="endTime">
-          <el-date-picker v-model="form.endTime" type="datetime" value-format="YYYY-MM-DD HH:mm:ss" class="w-full" />
+          <el-date-picker
+            v-model="form.endTime"
+            type="datetime"
+            value-format="YYYY-MM-DD HH:mm:ss"
+            :disabled-date="disablePastDate"
+            class="w-full"
+          />
         </el-form-item>
       </el-form>
       <template #footer>
@@ -187,6 +199,9 @@ const formRef = ref<FormInstance>()
 const flashSales = ref<FlashSale[]>([])
 const currentItem = ref<FlashSale | null>(null)
 const productOptions = ref<AdminProductRow[]>([])
+const TIME_FORMAT = 'YYYY-MM-DD HH:mm:ss'
+const CREATE_START_LEAD_MINUTES = 5
+const CREATE_DURATION_DAYS = 1
 
 const query = reactive({
   keyword: '',
@@ -206,13 +221,16 @@ const stats = reactive<AdminFlashSaleStats>({
   endedFlashSales: 0,
 })
 
+const buildDefaultStartTime = () => dayjs().add(CREATE_START_LEAD_MINUTES, 'minute').startOf('minute').format(TIME_FORMAT)
+const buildDefaultEndTime = (startTime = buildDefaultStartTime()) => dayjs(startTime).add(CREATE_DURATION_DAYS, 'day').format(TIME_FORMAT)
+
 const form = reactive({
   id: 0,
   productId: undefined as number | undefined,
   flashPrice: 0.01,
   flashStock: 1,
-  startTime: '',
-  endTime: '',
+  startTime: buildDefaultStartTime(),
+  endTime: buildDefaultEndTime(),
 })
 
 const rules: FormRules = {
@@ -254,13 +272,38 @@ const getStockRate = (item: FlashSale) => {
   return Math.round((item.remainingStock / item.flashStock) * 100)
 }
 
+const disablePastDate = (date: Date) => dayjs(date).endOf('day').isBefore(dayjs())
+
+const validateTimeRange = () => {
+  const now = dayjs()
+  const startTime = dayjs(form.startTime)
+  const endTime = dayjs(form.endTime)
+
+  if (!startTime.isValid() || !endTime.isValid()) {
+    ElMessage.error('开始时间或结束时间格式无效')
+    return false
+  }
+
+  if (!startTime.isAfter(now)) {
+    ElMessage.error('开始时间必须晚于当前时间')
+    return false
+  }
+
+  if (!endTime.isAfter(startTime)) {
+    ElMessage.error('结束时间必须晚于开始时间')
+    return false
+  }
+
+  return true
+}
+
 const resetForm = () => {
   form.id = 0
   form.productId = undefined
   form.flashPrice = 0.01
   form.flashStock = 1
-  form.startTime = ''
-  form.endTime = ''
+  form.startTime = buildDefaultStartTime()
+  form.endTime = buildDefaultEndTime(form.startTime)
 }
 
 const loadStats = async () => {
@@ -315,6 +358,7 @@ const submitForm = async () => {
 
   await formRef.value.validate(async (valid) => {
     if (!valid) return
+    if (!validateTimeRange()) return
 
     saving.value = true
     try {
@@ -435,19 +479,20 @@ onMounted(() => {
 }
 
 .mini-stat {
-  @apply rounded-xl text-white p-5 shadow-sm;
-
-  &.purple { background: linear-gradient(135deg, #8b5cf6, #7c3aed); }
-  &.red { background: linear-gradient(135deg, #ef4444, #dc2626); }
-  &.orange { background: linear-gradient(135deg, #f59e0b, #ea580c); }
-  &.gray { background: linear-gradient(135deg, #64748b, #475569); }
+  @apply rounded-xl p-5 shadow-sm;
+  background: #fffaf2;
+  color: #171715;
+  border: 1px solid #d8cebf;
+  box-shadow: 0 10px 24px rgba(23, 22, 20, 0.04);
 
   &__value { @apply text-3xl font-bold; }
   &__label { @apply text-sm opacity-90 mt-2; }
 }
 
 .panel-card {
-  @apply bg-white rounded-xl shadow-sm p-5;
+  @apply bg-white rounded-xl p-5;
+  border: 1px solid #d8cebf;
+  box-shadow: 0 10px 24px rgba(23, 22, 20, 0.04);
 }
 
 .filter-card {
@@ -468,7 +513,7 @@ onMounted(() => {
   height: 56px;
   object-fit: cover;
   border-radius: 12px;
-  border: 1px solid #e2e8f0;
+  border: 1px solid #d8cebf;
 }
 
 .detail-image {
@@ -499,7 +544,8 @@ onMounted(() => {
 }
 
 .flash-price {
-  @apply text-3xl font-bold text-rose-500;
+  @apply text-3xl font-bold;
+  color: #171715;
 }
 
 .origin-price {