feat: v1.2 数据可视化与统计增强

新增功能：
- uCharts 集成，支持环形图和折线图
- 统计页分类占比环形图
- 统计页每日趋势折线图
- 统计页增加最大单笔和对比上月指标
- 首页今日支出卡片

组件：
- ChartWrapper 通用图表组件（支持 pie/line/column）
- 支持 H5 和微信小程序双端

依赖：
- 新增 @qiun/ucharts 图表库

client/src/pages/index/index.vue

@@ -36,6 +36,20 @@
       </view>
     </view>
 
+    <view class="today-card" v-if="!loading">
+      <view class="today-left">
+        <text class="today-label">今日支出</text>
+        <text class="today-amount">{{ formatAmount(todayExpense) }}</text>
+      </view>
+      <view class="today-right">
+        <text class="today-count">{{ todayCount }}笔</text>
+      </view>
+    </view>
+    <view class="today-card" v-else>
+      <Skeleton width="200rpx" height="28rpx" variant="text" />
+      <Skeleton width="160rpx" height="48rpx" variant="rect" />
+    </view>
+
     <view class="quick-actions">
       <view class="quick-btn" @tap="goAdd('expense')">
         <SvgIcon name="trend-down" :size="48" color="#FF6B6B" />
@@ -103,6 +117,8 @@ const budget = ref<any>(null)
 const recentTx = ref<any[]>([])
 const loading = ref(true)
 const loadError = ref(false)
+const todayExpense = ref(0)
+const todayCount = ref(0)
 
 const greeting = computed(() => {
   const h = new Date().getHours()
@@ -117,10 +133,12 @@ async function loadData() {
   try {
     loading.value = true
     loadError.value = false
+    const today = new Date().toISOString().slice(0, 10)
     await Promise.all([
       statsStore.fetchOverview(),
       budgetStore.fetchBudget(),
-      txStore.fetchTransactions({ page: 1 })
+      txStore.fetchTransactions({ page: 1 }),
+      fetchTodayExpense(today)
     ])
     overview.value = statsStore.overview
     budget.value = budgetStore.budget
@@ -133,6 +151,21 @@ async function loadData() {
   }
 }
 
+async function fetchTodayExpense(today: string) {
+  try {
+    const { request } = await import('@/utils/request')
+    const data = await request<any>({
+      url: '/transactions',
+      data: { page: 1, pageSize: 100, type: 'expense', startDate: today, endDate: today }
+    })
+    todayExpense.value = data.list.reduce((sum: number, t: any) => sum + t.amount, 0)
+    todayCount.value = data.list.length
+  } catch {
+    todayExpense.value = 0
+    todayCount.value = 0
+  }
+}
+
 onMounted(() => loadData())
 
 // Refresh data when returning from other pages (e.g., after adding a transaction)
@@ -270,6 +303,45 @@ function goBills() {
   &.expense { color: #FF6B6B; }
 }
 
+.today-card {
+  margin: 24rpx 40rpx 0;
+  padding: 28rpx 32rpx;
+  background: #FFFFFF;
+  border-radius: 28rpx;
+  border: 2rpx solid #F0E0D6;
+  box-shadow: 4rpx 4rpx 12rpx rgba(45, 27, 27, 0.08);
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+}
+
+.today-left {
+  display: flex;
+  flex-direction: column;
+  gap: 8rpx;
+}
+
+.today-label {
+  font-size: 24rpx;
+  color: #8B7E7E;
+}
+
+.today-amount {
+  font-family: 'Fredoka', sans-serif;
+  font-size: 36rpx;
+  font-weight: 600;
+  color: #FF6B6B;
+}
+
+.today-right {
+  text-align: right;
+}
+
+.today-count {
+  font-size: 24rpx;
+  color: #8B7E7E;
+}
+
 .quick-actions {
   display: flex;
   gap: 24rpx;