Add performance regression detection: indexes, timing middleware, benchmark script

Nightshift-Task: perf-regression
Nightshift-Ref: https://github.com/marcus/nightshift

server/package.json

@@ -6,7 +6,8 @@
     "start": "node src/index.js",
     "dev": "nodemon src/index.js",
     "test": "vitest run",
-    "test:watch": "vitest"
+    "test:watch": "vitest",
+    "perf": "node ../scripts/perf-benchmark.js"
   },
   "dependencies": {
     "cors": "^2.8.5",

server/src/app.js

@@ -9,11 +9,13 @@ const actualsRouter = require('./routes/actuals');
 const oneTimeExpensesRouter = require('./routes/one-time-expenses');
 const summaryRouter = require('./routes/summary');
 const { router: financingRouter } = require('./routes/financing');
+const timingMiddleware = require('./middleware/timing');
 
 const app = express();
 
 app.use(cors());
 app.use(express.json());
+app.use(timingMiddleware);
 
 // API routes
 app.use('/api', healthRouter);

server/src/middleware/timing.js

@@ -0,0 +1,21 @@
+'use strict';
+
+const SLOW_THRESHOLD_MS = 200;
+
+function timingMiddleware(req, res, next) {
+  const start = Date.now();
+
+  res.on('finish', () => {
+    const duration = Date.now() - start;
+    const msg = `${req.method} ${req.path} ${res.statusCode} ${duration}ms`;
+    if (duration >= SLOW_THRESHOLD_MS) {
+      console.warn(`[SLOW] ${msg}`);
+    } else {
+      console.log(`[timing] ${msg}`);
+    }
+  });
+
+  next();
+}
+
+module.exports = timingMiddleware;