refactor(energy): 氢能总览参照 BI 重构 + 月度趋势 + 高密度 KPI

参考 https://bi.lnh2e.com/lingniu/decision/link/0iqP 重新设计：
- 4 张高密度 KPI 卡：累计加氢量 / 累计加氢费 / 本月加氢 / 本日加氢
  每张含主指标 + 2 行明细（我司/客户、加氢费/占比）
- 新增年内月度加氢量柱图（缺失月份补 0）
- 数字格式化：万元/亿元/T 单位自动切换，tabular-nums 对齐
- 后端 /hydrogen/overview 增加 monthly 字段
- 骨架屏同步更新

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

src/server/routes/energy/index.ts

@@ -165,7 +165,33 @@ app.get('/hydrogen/overview', async (c) => {
     ...(restKg > 0 ? [{ region: '其他', kg: restKg, share: restKg / totalKg }] : []),
   ];
 
-  return { kpi, top5, regions };
+  // 月度趋势（本年内 12 个月，缺失月补 0）
+  const [monthRows] = await pool.query<RowDataPacket[]>(
+    `SELECT DATE_FORMAT(hydrogen_time, '%Y-%m') AS m,
+            ROUND(SUM(hydrogen_quantity), 2) AS kg,
+            ROUND(SUM(cost_expense), 2) AS fee
+     FROM tab_energy_hydrogen_bill
+     WHERE is_deleted = 0
+       AND hydrogen_time >= ?
+       AND YEAR(hydrogen_time) = YEAR(CURDATE())
+     GROUP BY m
+     ORDER BY m`,
+    [HYDROGEN_MIN_DATE],
+  );
+  const monthMap = new Map<string, { kg: number; fee: number }>();
+  for (const r of monthRows) {
+    monthMap.set(r.m as string, { kg: Number(r.kg) || 0, fee: Number(r.fee) || 0 });
+  }
+  const year = new Date().getFullYear();
+  const currentMonth = new Date().getMonth() + 1;
+  const monthly: { month: string; kg: number; fee: number }[] = [];
+  for (let mi = 1; mi <= currentMonth; mi++) {
+    const key = `${year}-${String(mi).padStart(2, '0')}`;
+    const v = monthMap.get(key) || { kg: 0, fee: 0 };
+    monthly.push({ month: key, kg: v.kg, fee: v.fee });
+  }
+
+  return { kpi, top5, regions, monthly };
   });
   return c.json(data);
 });