Add: backend dir and moved frontend to frontend dir

frontend/src/api/axiosInstance.js

@@ -0,0 +1,14 @@
+import axios from "axios";
+
+const createAxiosInstance = (baseURL, token) => {
+  const instance = axios.create({
+    baseURL,
+    headers: {
+      ...(token && { Authorization: `Bearer ${token}` }),
+    },
+  });
+
+  return instance;
+};
+
+export default createAxiosInstance;