scaffold backend with hono/bun

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/src/index.ts

@@ -0,0 +1,13 @@
+import { Hono } from "hono";
+import { cors } from "hono/cors";
+
+const app = new Hono();
+
+app.use("*", cors());
+
+app.get("/health", (c) => c.json({ status: "ok" }));
+
+export default {
+	port: Number(process.env.PORT ?? 3000),
+	fetch: app.fetch,
+};