[#12] 파일명 kebab case로 수정, prettier 설정 적용

package.json

@@ -10,6 +10,7 @@
     "preview": "vite preview"
   },
   "dependencies": {
+    "axios": "^1.11.0",
     "react": "^19.1.1",
     "react-dom": "^19.1.1",
     "styled-components": "^6.1.19"

src/api/axios-instance.js

@@ -0,0 +1,9 @@
+import axios from "axios";
+
+const axiosInstance = axios.create({
+  baseURL: "https://rolling-api.vercel.app/",
+  timeout: 5000,
+  headers: { "Content-Type": "application/json" },
+});
+
+export default axiosInstance;