fix: use app.use() for SPA fallback instead of Express 5 incompatible wildcards

luckychit/web-server.js

@@ -47,7 +47,7 @@ app.use(express.static(BUILD_DIR, {
 
 // Handle Flutter routes (SPA - Single Page Application)
 // Any route not found as a static file should serve index.html
-app.get('/*', (req, res) => {
+app.use( (req, res) => {
   res.sendFile(path.join(BUILD_DIR, 'index.html'));
 });