fix: bust npm build cache to force fresh React dist

frontend/vite.config.js

@@ -1,3 +1,4 @@
+// cache-bust: 2
 import { defineConfig } from "vite";
 import react from "@vitejs/plugin-react";
-export default defineConfig({ plugins: [react()], server: { port: 5173 } });
+export default defineConfig({ plugins: [react()], server: { port: 5173 } });