fix: exclude static files from SPA catch-all route

Files with extensions (.onnx, .wasm, etc.) now bypass the SPA handler,
allowing the static middleware to serve them correctly. This fixes
ONNX model loading which was incorrectly returning index.html.

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

trigo-web/backend/src/server.ts

@@ -72,11 +72,17 @@ if (process.env.NODE_ENV === "production") {
 	const frontendPath = path.join(__dirname, "../../app/dist");
 	app.use(express.static(frontendPath));
 
-	// Serve index.html for all routes (SPA support)
+	// Serve index.html for SPA routes (paths without file extensions)
 	app.get("*", (req: any, res: any, next: any) => {
+		// Skip API and socket.io routes
 		if (req.path.startsWith("/health") || req.path.startsWith("/socket.io")) {
 			return next();
 		}
+		// Skip requests for files with extensions (let static middleware handle them or return 404)
+		if (path.extname(req.path)) {
+			return next();
+		}
+		// Serve index.html for SPA navigation routes
 		res.sendFile(path.join(frontendPath, "index.html"));
 	});
 }