feat: Add OAuth state parameter handling in sign-in flow

src/app/(auth)/sign-in/page.tsx

@@ -48,7 +48,7 @@ export default function LoginPage({ searchParams }: Props) {
             <span style={{ fontFamily: "Bahamas Bold" }}>Q58 Connect</span>
           </div>
         </div>
-        <UserAuthForm />
+        <UserAuthForm oauthState={searchParams.state} />
         <p className="px-8 text-center text-sm text-muted-foreground">
           By clicking continue, you agree to our{" "}
           <Link

src/components/auth/user-auth-form.tsx

@@ -12,10 +12,15 @@ interface DiscourseData {
   sso_url: string;
 }
 
+interface UserAuthFormProps extends React.HTMLAttributes<HTMLDivElement> {
+  oauthState?: string;
+}
+
 export function UserAuthForm({
   className,
+  oauthState,
   ...props
-}: React.HTMLAttributes<HTMLDivElement>) {
+}: UserAuthFormProps) {
   const [isLoading, setIsLoading] = React.useState<boolean>(false);
   const router = useRouter();
   const { toast } = useToast();
@@ -23,6 +28,17 @@ export function UserAuthForm({
   const signIn = () => {
     React.startTransition(async () => {
       try {
+        // 如果有 OAuth 参数，先保存到 cookie
+        if (oauthState) {
+          await fetch("/api/auth/oauth-state", {
+            method: "POST",
+            headers: {
+              "Content-Type": "application/json",
+            },
+            body: JSON.stringify({ state: oauthState }),
+          });
+        }
+
         const response = await fetch("/api/auth/q58", {
           method: "POST",
           headers: {