feat(energy): connect to real DB (lingniu_prod)

Replace front-end mock data with live API backed by:
- tab_energy_hydrogen_bill (66.5K rows) joined with
  tab_hydrogen_site (internal stations) and tab_outside_hydrogen_site
  (external stations, joined via inner_site_id)
- tab_energy_electricity_bill (4.4K rows, all 龙王路充电站)

New server routes (src/server/routes/energy/):
- GET /api/energy/hydrogen/overview  → KPI + Top5 站点 + 区域占比
- GET /api/energy/hydrogen/daily?range=&customer=  → 日级 + 站点级下钻
- GET /api/energy/electric/overview  → KPI + 本月柱图 (fallback to last
  available month if current month has no data)
- GET /api/energy/electric/monthly?customer=  → 6 个月分组日级表

Business rules encoded server-side:
- 客户类型: customer_id IS NULL = 羚牛承担, NOT NULL = 外部
- 时区: DATETIME 列字面值是 UTC，分组前 +8h 转成 CST
- 数据清理: hydrogen_time >= 2024-01-01 (排除 1900 年脏数据)
- 站点名 fallback: short_name → name → fixed_station_name → station_name → '未知站点'
- 区域归一化: SUBSTRING_INDEX(city, '-', -1) 取最后一段，去掉 '省'/'市'
  让 '四川省-成都市' 和 '成都市' 合并为 '成都'

Component changes:
- All 4 components (HydrogenOverview, HydrogenDaily, ElectricOverview,
  ElectricDaily) now use useEffect + fetch with loading/error states
- HydrogenDaily filtering moved to server (range + customer params)
  → drops client-side TODAY constant + isInPick switch
- ElectricOverview chart title is dynamic: shows 'YYYY-MM 每日充电'
  when fallback kicks in (current month has no data)
- mock.ts deleted

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/modules/energy/ElectricOverview.tsx

@@ -1,8 +1,8 @@
-import { useMemo } from 'react';
+import { useEffect, useState } from 'react';
 import { Wallet, BatteryCharging, CalendarClock } from 'lucide-react';
 import { BarChart, Bar, XAxis, YAxis, ResponsiveContainer, Cell, Tooltip } from 'recharts';
 import TrendBadge from './TrendBadge';
-import { ELECTRIC_KPI, ELECTRIC_MONTHLY } from './mock';
+import { fetchElectricOverview, type ElectricOverviewResponse } from './api';
 
 function fmtYuan(yuan: number) {
   return `¥${yuan.toLocaleString('zh-CN', { maximumFractionDigits: 2 })}`;
@@ -12,15 +12,32 @@ function fmtKwh(kwh: number) {
 }
 
 export default function ElectricOverview() {
-  const k = ELECTRIC_KPI;
+  const [data, setData] = useState<ElectricOverviewResponse | null>(null);
+  const [error, setError] = useState<string | null>(null);
 
-  // 本月每日数据（按日期升序，便于柱图按时间从左到右展示）
-  const trendData = useMemo(() => {
-    const first = ELECTRIC_MONTHLY[0];
-    if (!first) return [];
-    return [...first.rows].sort((a, b) => a.date.localeCompare(b.date));
+  useEffect(() => {
+    let cancelled = false;
+    fetchElectricOverview()
+      .then(d => { if (!cancelled) setData(d); })
+      .catch(e => { if (!cancelled) setError(e instanceof Error ? e.message : String(e)); });
+    return () => { cancelled = true; };
   }, []);
 
+  if (error) {
+    return <div className="bg-red-50 text-red-600 rounded-2xl border border-red-100 p-4 text-sm">加载失败：{error}</div>;
+  }
+  if (!data) {
+    return <div className="bg-white rounded-2xl border border-slate-100 shadow-sm p-6 text-center text-slate-400 text-sm">加载中…</div>;
+  }
+  const k = data.kpi;
+  const trendData = data.trend;
+  // 当电能数据滞后（本月无数据走 fallback）时，柱图标题显示实际月份
+  const trendMonthLabel = trendData[0]?.date.slice(0, 7);
+  const currentMonth = new Date().toISOString().slice(0, 7);
+  const chartTitle = trendMonthLabel && trendMonthLabel !== currentMonth
+    ? `${trendMonthLabel} 每日充电`
+    : '本月每日充电';
+
   return (
     <div className="flex flex-col gap-3">
       {/* 横向 mini KPI 头 */}
@@ -52,7 +69,7 @@ export default function ElectricOverview() {
       {/* 本月每日充电柱图 */}
       <div className="bg-white rounded-2xl border border-slate-100 shadow-sm p-4">
         <div className="flex items-center justify-between mb-2">
-          <span className="text-sm font-bold text-slate-700">本月每日充电</span>
+          <span className="text-sm font-bold text-slate-700">{chartTitle}</span>
           <span className="text-[11px] text-slate-400 font-bold">单位 元</span>
         </div>
         <ResponsiveContainer width="100%" height={160}>