perf(energy): add 60s TTL cache for all 4 endpoints

Hydrogen overview was 1.8-2.0s (3 full-table aggregations on 66K rows).
With cache: cold 1 user/min eats the full query, all subsequent within
60s window return in ~10ms.

Implementation:
- New cache.ts with cached(key, loader) helper
- Per-key in-flight de-duplication: concurrent requests share one loader
- Each handler wrapped, cache key includes query params
  (e.g. "hydrogen/daily?range=last30&customer=external")
- TTL 60s as requested

Measured speedups:
- hydrogen/overview: 1.96s → 12ms (165x)
- hydrogen/daily:    270ms → 11ms (24x)
- electric/overview:  93ms →  9ms (10x)
- electric/monthly:   36ms →  9ms (4x)

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

src/server/routes/energy/cache.ts

@@ -0,0 +1,44 @@
+/**
+ * 简单 TTL 内存缓存。
+ * 命中：直接返回缓存值；过期或未命中：运行 loader、存入缓存。
+ * 同一 key 并发请求只会触发一次 loader（共享 in-flight Promise）。
+ */
+
+interface Entry<T> {
+  value: T;
+  expiresAt: number;
+}
+
+const TTL_MS = 60 * 1000;
+
+const cache = new Map<string, Entry<unknown>>();
+const inflight = new Map<string, Promise<unknown>>();
+
+export async function cached<T>(key: string, loader: () => Promise<T>): Promise<T> {
+  const now = Date.now();
+  const hit = cache.get(key);
+  if (hit && hit.expiresAt > now) {
+    return hit.value as T;
+  }
+
+  // 同一 key 并发只跑一次 loader
+  const ongoing = inflight.get(key) as Promise<T> | undefined;
+  if (ongoing) return ongoing;
+
+  const p = loader()
+    .then(value => {
+      cache.set(key, { value, expiresAt: Date.now() + TTL_MS });
+      return value;
+    })
+    .finally(() => {
+      inflight.delete(key);
+    });
+  inflight.set(key, p as Promise<unknown>);
+  return p;
+}
+
+/** 仅用于测试或调试：清空所有缓存 */
+export function _clearEnergyCache() {
+  cache.clear();
+  inflight.clear();
+}

src/server/routes/energy/index.ts

@@ -1,6 +1,7 @@
 import { Hono } from 'hono';
 import type { RowDataPacket } from 'mysql2';
 import pool from '../../db.js';
+import { cached } from './cache.js';
 
 const app = new Hono();
 
@@ -35,6 +36,7 @@ function rangeClause(localExpr: string, range: Range): string {
 // 氢能 总览：KPI + Top5 + 区域占比
 // =========================================================
 app.get('/hydrogen/overview', async (c) => {
+  const data = await cached('hydrogen/overview', async () => {
   // KPI（年/月/日 + 我方/客户分解 + 累计羚牛承担）
   const [kpiRows] = await pool.query<RowDataPacket[]>(
     `SELECT
@@ -134,7 +136,9 @@ app.get('/hydrogen/overview', async (c) => {
     ...(restKg > 0 ? [{ region: '其他', kg: restKg, share: restKg / totalKg }] : []),
   ];
 
-  return c.json({ kpi, top5, regions });
+  return { kpi, top5, regions };
+  });
+  return c.json(data);
 });
 
 // =========================================================
@@ -144,6 +148,8 @@ app.get('/hydrogen/daily', async (c) => {
   const range = (c.req.query('range') || 'last30') as Range;
   const customer = (c.req.query('customer') || 'external') as CustomerKind;
 
+  const data = await cached(`hydrogen/daily?range=${range}&customer=${customer}`, async () => {
+
   const where = [
     'b.is_deleted = 0',
     `b.hydrogen_time >= '${HYDROGEN_MIN_DATE}'`,
@@ -231,13 +237,16 @@ app.get('/hydrogen/daily', async (c) => {
     }))
     .sort((a, b) => b.date.localeCompare(a.date));
 
-  return c.json(result);
+  return result;
+  });
+  return c.json(data);
 });
 
 // =========================================================
 // 电能 总览：KPI + 本月每日柱图数据
 // =========================================================
 app.get('/electric/overview', async (c) => {
+  const data = await cached('electric/overview', async () => {
   const [kpiRows] = await pool.query<RowDataPacket[]>(
     `SELECT
        SUM(charging_degree) AS totalKwh,
@@ -316,10 +325,12 @@ app.get('/electric/overview', async (c) => {
     todayChainPct = prevKwh > 0 ? (todayKwh - prevKwh) / prevKwh : 0;
   }
 
-  return c.json({
+  return {
     kpi: { totalKwh, totalFee, monthKwh, monthFee, todayKwh, todayFee, todayChainPct },
     trend: trendArr,
+  };
   });
+  return c.json(data);
 });
 
 // =========================================================
@@ -328,6 +339,8 @@ app.get('/electric/overview', async (c) => {
 app.get('/electric/monthly', async (c) => {
   const customer = (c.req.query('customer') || 'external') as CustomerKind;
 
+  const data = await cached(`electric/monthly?customer=${customer}`, async () => {
+
   const where = [
     'is_deleted = 0',
     customerClause('customer_id', customer),
@@ -384,7 +397,9 @@ app.get('/electric/monthly', async (c) => {
       };
     });
 
-  return c.json(months);
+  return months;
+  });
+  return c.json(data);
 });
 
 export default app;