feat(dashboard): add classroom/attendance/income stat cards and trend charts

- Add second row of stat cards: classroom count, occupancy rate, attendance rate, monthly income
- Add ECharts line charts for attendance trend (30-day) and income trend (6-month)
- All fields sourced from existing GET /dashboard/stats response (Task 7.1 contract)

apps/admin/src/pages/Dashboard/index.tsx

@@ -1,6 +1,6 @@
 import React, { useEffect, useState } from 'react';
 import { Row, Col, Card, Statistic, DatePicker, Spin, Grid } from 'antd';
-import { TeamOutlined, HomeOutlined, DollarOutlined, CheckCircleOutlined } from '@ant-design/icons';
+import { TeamOutlined, HomeOutlined, DollarOutlined, CheckCircleOutlined, BankOutlined, PercentageOutlined, UserSwitchOutlined } from '@ant-design/icons';
 import ReactECharts from 'echarts-for-react';
 import dayjs from 'dayjs';
 import api from '../../api';
@@ -156,6 +156,49 @@ const DashboardPage: React.FC = () => {
     ],
   };
 
+  // 考勤趋势折线图
+  const attendanceLineOption = {
+    tooltip: { trigger: 'axis' },
+    grid: { left: 50, right: 20, bottom: 30, top: 10 },
+    xAxis: {
+      type: 'category',
+      data: (stats?.attendanceTrend || []).map((d: { date: string }) => d.date),
+      axisLabel: { rotate: 45, fontSize: 10 },
+    },
+    yAxis: { type: 'value', min: 0, max: 100, axisLabel: { formatter: '{value}%' } },
+    series: [
+      {
+        type: 'line',
+        data: (stats?.attendanceTrend || []).map((d: { rate: string }) => parseFloat(d.rate) || 0),
+        smooth: true,
+        lineStyle: { color: '#007AFF', width: 2 },
+        itemStyle: { color: '#007AFF' },
+        areaStyle: { color: 'rgba(0,122,255,0.1)' },
+      },
+    ],
+  };
+
+  // 收入趋势折线图
+  const incomeLineOption = {
+    tooltip: { trigger: 'axis', valueFormatter: (v: number) => `¥${v.toLocaleString()}` },
+    grid: { left: 70, right: 20, bottom: 30, top: 10 },
+    xAxis: {
+      type: 'category',
+      data: (stats?.incomeTrend || []).map((d: { month: string }) => d.month),
+    },
+    yAxis: { type: 'value', axisLabel: { formatter: (v: number) => `¥${(v / 10000).toFixed(0)}万` } },
+    series: [
+      {
+        type: 'line',
+        data: (stats?.incomeTrend || []).map((d: { amount: number }) => d.amount),
+        smooth: true,
+        lineStyle: { color: '#34C759', width: 2 },
+        itemStyle: { color: '#34C759' },
+        areaStyle: { color: 'rgba(52,199,89,0.1)' },
+      },
+    ],
+  };
+
   if (loading && !stats)
     return <Spin size="large" style={{ display: 'block', margin: '100px auto' }} />;
 
@@ -217,6 +260,44 @@ const DashboardPage: React.FC = () => {
         </Col>
       </Row>
 
+      <Row gutter={[16, 16]} style={{ marginBottom: 24 }}>
+        <Col xs={12} sm={12} md={6}>
+          <Card>
+            <Statistic title="教室总数" value={stats?.classroomCount || 0} prefix={<BankOutlined />} />
+          </Card>
+        </Col>
+        <Col xs={12} sm={12} md={6}>
+          <Card>
+            <Statistic
+              title="教室占用率"
+              value={stats?.classroomOccupancyRate || 0}
+              suffix="%"
+              prefix={<PercentageOutlined />}
+            />
+          </Card>
+        </Col>
+        <Col xs={12} sm={12} md={6}>
+          <Card>
+            <Statistic
+              title="今日出勤率"
+              value={stats?.todayAttendanceRate || 0}
+              suffix="%"
+              prefix={<UserSwitchOutlined />}
+            />
+          </Card>
+        </Col>
+        <Col xs={12} sm={12} md={6}>
+          <Card>
+            <Statistic
+              title="本月收入"
+              value={stats?.monthlyIncome || 0}
+              precision={2}
+              prefix="¥"
+            />
+          </Card>
+        </Col>
+      </Row>
+
       <Card title="入住时间线（甘特图）" style={{ marginBottom: 24 }}>
         {ganttData.length > 0 ? (
           <ReactECharts
@@ -228,6 +309,27 @@ const DashboardPage: React.FC = () => {
         )}
       </Card>
 
+      <Row gutter={[16, 16]} style={{ marginBottom: 24 }}>
+        <Col xs={24} sm={12}>
+          <Card title="考勤趋势（近30天）">
+            {(stats?.attendanceTrend || []).length > 0 ? (
+              <ReactECharts option={attendanceLineOption} style={{ width: '100%', height: isMobile ? 250 : 300 }} />
+            ) : (
+              <div style={{ textAlign: 'center', padding: 40, color: '#999' }}>暂无考勤数据</div>
+            )}
+          </Card>
+        </Col>
+        <Col xs={24} sm={12}>
+          <Card title="收入趋势（近6个月）">
+            {(stats?.incomeTrend || []).length > 0 ? (
+              <ReactECharts option={incomeLineOption} style={{ width: '100%', height: isMobile ? 250 : 300 }} />
+            ) : (
+              <div style={{ textAlign: 'center', padding: 40, color: '#999' }}>暂无收入数据</div>
+            )}
+          </Card>
+        </Col>
+      </Row>
+
       <Row gutter={[16, 16]}>
         <Col xs={24} sm={12}>
           <Card title="费用类型分布">