[FA-misc] Fixes refresh token usage hopefully

fictionarchive-web-astro/src/lib/auth/authStore.ts

@@ -117,3 +117,14 @@ export async function logout() {
     user.set(null);
   }
 }
+
+export async function refreshToken(): Promise<User | null> {
+  if (!userManager) return null;
+  try {
+    const newUser = await userManager.signinSilent();
+    return newUser;
+  } catch (e) {
+    console.error('Token refresh failed:', e);
+    return null;
+  }
+}