fix: 里程环比改为真实值（与前一天对比）

- 后端缓存刷新时查询前一天总里程（yesterdayTotal）
- 前端计算真实环比：(今日-昨日)/昨日*100%
- 上涨显示蓝色↑，下跌显示红色↓
- 昨日无数据时不显示环比

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/server/routes/mileage.ts

@@ -43,7 +43,7 @@ interface CachedVehicle {
 
 interface MonitoringCache {
   vehicles: CachedVehicle[];
-  stats: { totalToday: number; totalAll: number; vehicleCount: number };
+  stats: { totalToday: number; totalAll: number; vehicleCount: number; yesterdayTotal: number };
   filters: { departments: string[]; customers: string[]; plates: string[]; projects: string[]; entities: string[] };
   updatedAt: string;
 }
@@ -56,7 +56,7 @@ async function refreshMonitoringCache() {
     const start = Date.now();
 
     // 并行查询两个数据库
-    const [mileageResult, infoRows] = await Promise.all([
+    const [mileageResult, yesterdayResult, infoRows] = await Promise.all([
       (async () => {
         const [dateRows] = await mileagePool.execute(
           'SELECT MAX(stat_date) as latest FROM v_vehicle_daily_stats'
@@ -70,6 +70,13 @@ async function refreshMonitoringCache() {
         ) as any;
         return rows;
       })(),
+      (async () => {
+        const [rows] = await mileagePool.execute(
+          `SELECT SUM(daily_km) as total FROM v_vehicle_daily_stats
+           WHERE stat_date = DATE_SUB((SELECT MAX(stat_date) FROM v_vehicle_daily_stats), INTERVAL 1 DAY)`
+        ) as any;
+        return Number(rows[0]?.total) || 0;
+      })(),
       pool.execute(VEHICLE_INFO_SQL).then(([rows]) => rows as any[]),
     ]);
 
@@ -130,7 +137,7 @@ async function refreshMonitoringCache() {
 
     monitoringCache = {
       vehicles,
-      stats: { totalToday, totalAll, vehicleCount: vehicles.length },
+      stats: { totalToday, totalAll, vehicleCount: vehicles.length, yesterdayTotal: yesterdayResult },
       filters: { departments, customers, plates, projects, entities },
       updatedAt: new Date().toISOString(),
     };
@@ -148,7 +155,7 @@ setInterval(refreshMonitoringCache, 2 * 60 * 1000);
 // GET /monitoring — 从缓存取数据，支持筛选/排序/分页
 app.get('/monitoring', (c) => {
   if (!monitoringCache) {
-    return c.json({ vehicles: [], stats: { totalToday: 0, totalAll: 0, vehicleCount: 0 }, filters: { departments: [], customers: [], plates: [], projects: [], entities: [] }, total: 0, page: 1, totalPages: 1, updatedAt: new Date().toISOString() });
+    return c.json({ vehicles: [], stats: { totalToday: 0, totalAll: 0, vehicleCount: 0, yesterdayTotal: 0 }, filters: { departments: [], customers: [], plates: [], projects: [], entities: [] }, total: 0, page: 1, totalPages: 1, updatedAt: new Date().toISOString() });
   }
 
   const sortBy = c.req.query('sortBy') || 'today';
@@ -190,6 +197,7 @@ app.get('/monitoring', (c) => {
     totalToday: vehicles.reduce((sum, v) => sum + v.dailyKm, 0),
     totalAll: vehicles.reduce((sum, v) => sum + (v.totalKm || 0), 0),
     vehicleCount: vehicles.length,
+    yesterdayTotal: monitoringCache.stats.yesterdayTotal,
   };
 
   // 排序