added api logic, vitest, minimal testing ui

api/tests/appFactory.ts

@@ -0,0 +1,8 @@
+import type { FastifyInstance } from "fastify";
+
+export default async function appFactory(): Promise<FastifyInstance> {
+  // env is already set in tests/setup.ts, so now we can import
+  const { default: app } = await import("../src/server"); // ESM + TLA safe
+  await app.ready(); // ensure all plugins registered
+  return app;
+}