fix app.tsx no –crypto.randomUUID is not a function error

frontend/src/App.tsx

@@ -39,6 +39,21 @@ async function createCodeVerifier() {
   return base64UrlEncode(array)
 }
 
+function generateUUID() {
+  // Use native crypto.randomUUID when available, otherwise fallback to RFC4122 v4
+  // Compatible with older browsers that lack crypto.randomUUID
+  if (typeof crypto !== 'undefined' && 'randomUUID' in crypto) {
+    // @ts-ignore
+    return (crypto as any).randomUUID()
+  }
+
+  const bytes = crypto.getRandomValues(new Uint8Array(16))
+  bytes[6] = (bytes[6] & 0x0f) | 0x40
+  bytes[8] = (bytes[8] & 0x3f) | 0x80
+  const hex = Array.from(bytes, (b) => b.toString(16).padStart(2, '0')).join('')
+  return `${hex.substr(0, 8)}-${hex.substr(8, 4)}-${hex.substr(12, 4)}-${hex.substr(16, 4)}-${hex.substr(20, 12)}`
+}
+
 function getLocalToken() {
   return window.localStorage.getItem('oidc_access_token')
 }
@@ -137,7 +152,7 @@ function App() {
   async function login() {
     try {
       const config = await fetchOIDCConfig()
-      const state = crypto.randomUUID()
+      const state = generateUUID()
       const codeVerifier = await createCodeVerifier()
       const codeChallenge = await sha256(codeVerifier)