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/api.ts

@@ -0,0 +1,37 @@
+import { fetchJson } from '../../auth/api-client';
+import type {
+  HydrogenKpi, HydrogenStationTop, HydrogenRegionShare, HydrogenDailyRow,
+  ElectricKpi, ElectricDailyRow, ElectricMonthGroup,
+  CustomerType, DateQuickPick,
+} from './types';
+
+const BASE = '/api/energy';
+
+export interface HydrogenOverviewResponse {
+  kpi: HydrogenKpi;
+  top5: HydrogenStationTop[];
+  regions: HydrogenRegionShare[];
+}
+
+export function fetchHydrogenOverview(): Promise<HydrogenOverviewResponse> {
+  return fetchJson<HydrogenOverviewResponse>(`${BASE}/hydrogen/overview`);
+}
+
+export function fetchHydrogenDaily(range: DateQuickPick, customer: CustomerType): Promise<HydrogenDailyRow[]> {
+  const q = new URLSearchParams({ range, customer });
+  return fetchJson<HydrogenDailyRow[]>(`${BASE}/hydrogen/daily?${q.toString()}`);
+}
+
+export interface ElectricOverviewResponse {
+  kpi: ElectricKpi;
+  trend: ElectricDailyRow[];
+}
+
+export function fetchElectricOverview(): Promise<ElectricOverviewResponse> {
+  return fetchJson<ElectricOverviewResponse>(`${BASE}/electric/overview`);
+}
+
+export function fetchElectricMonthly(customer: CustomerType): Promise<ElectricMonthGroup[]> {
+  const q = new URLSearchParams({ customer });
+  return fetchJson<ElectricMonthGroup[]>(`${BASE}/electric/monthly?${q.toString()}`);
+}