feat: add backend

apps/server/middlewares/responseTime.ts

@@ -0,0 +1,13 @@
+import type { Middleware } from './types.ts';
+import type Koa from 'koa';
+
+export class ResponseTime implements Middleware {
+  apply(app: Koa): void {
+    app.use(async (ctx, next) => {
+      const start = Date.now();
+      await next();
+      const ms = Date.now() - start;
+      ctx.set('X-Response-Time', `${ms}ms`);
+    });
+  }
+}