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/server/index.ts

@@ -6,6 +6,7 @@ import dotenv from 'dotenv';
 import vehiclesRouter from './routes/vehicles.js';
 import mileageRouter from './routes/mileage/index.js';
 import schedulingRouter from './routes/scheduling/index.js';
+import energyRouter from './routes/energy/index.js';
 import { ensureSchedulingTables } from './routes/scheduling/db-schema.js';
 import authRouter from './auth/login.js';
 import { authMiddleware } from './auth/middleware.js';
@@ -25,6 +26,7 @@ app.use('/api/*', authMiddleware);
 app.route('/api/vehicles', vehiclesRouter);
 app.route('/api/mileage', mileageRouter);
 app.route('/api/scheduling', schedulingRouter);
+app.route('/api/energy', energyRouter);
 
 app.get('/api/health', (c) => c.json({ status: 'ok', time: new Date().toISOString() }));