feat(api): scaffold express server with /api/health endpoint

apps/api/src/app.ts

@@ -0,0 +1,12 @@
+import express from "express";
+import type { Express } from "express";
+
+export function createApp() {
+  const app: Express = express();
+
+  app.get("/api/health", (_req, res) => {
+    res.json({ status: "ok" });
+  });
+
+  return app;
+}