chore: update health check endpoint to return JSON response instead of plain text

Author: Stormix

apps/backend/src/api/health.ts

@@ -1,5 +1,5 @@
-import { Hono } from "hono";
+import { Hono } from 'hono';
 
-const health = new Hono().get("/", (c) => c.text("Health ok!"));
+const health = new Hono().get('/', (c) => c.json({ message: 'Health ok!' }));
 
 export default health;