add Pinia axios and VITE config to frontend.

frontend/src/utils/http/resolveAxiosErrorMessage.ts

@@ -0,0 +1,23 @@
+import axios from 'axios';
+
+export function resolveAxiosErrorMessage(error: unknown, fallback = 'Request failed'): string {
+    if (axios.isAxiosError(error)) {
+        const data = error.response?.data;
+        if (typeof data === 'object' && data !== null && 'message' in data) {
+            const message = (data as { message: unknown }).message;
+            if (typeof message === 'string') {
+                return message;
+            }
+            if (Array.isArray(message)) {
+                return message.map(String).join(', ');
+            }
+        }
+        if (error.message) {
+            return error.message;
+        }
+    }
+    if (error instanceof Error) {
+        return error.message;
+    }
+    return fallback;
+}