feat(web): add force password change redirect page

Add /auth/force-password-change route that handles the redirect flow
for Auth0 password change during login. The page preserves the Auth0
session state across the password change flow so users only need to
log in once.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: hexaforce

web/src/classic/components/pages/Authentication/ForcePasswordChange/index.tsx

@@ -0,0 +1,42 @@
+import { useEffect } from "react";
+
+import Loading from "@reearth/classic/components/atoms/Loading";
+import { getAuthInfo } from "@reearth/services/config";
+
+const STORAGE_KEY = "reearth_password_change_state";
+
+const ForcePasswordChangePage: React.FC = () => {
+  useEffect(() => {
+    const params = new URLSearchParams(window.location.search);
+    const ticket = params.get("ticket");
+    const state = params.get("state");
+
+    if (ticket && state) {
+      // Coming from Auth0 Post-Login Action redirect.
+      // Save state to sessionStorage so we can resume the login flow after password change.
+      sessionStorage.setItem(STORAGE_KEY, state);
+      // Redirect to Auth0's password change page.
+      window.location.href = ticket;
+      return;
+    }
+
+    // Coming back from Auth0 password change page (result_url redirect).
+    const savedState = sessionStorage.getItem(STORAGE_KEY);
+    if (savedState) {
+      sessionStorage.removeItem(STORAGE_KEY);
+      const authInfo = getAuthInfo();
+      if (authInfo?.auth0Domain) {
+        // Redirect back to Auth0 to complete the login flow.
+        window.location.href = `https://${authInfo.auth0Domain}/continue?state=${savedState}`;
+        return;
+      }
+    }
+
+    // Fallback: redirect to top page.
+    window.location.href = "/";
+  }, []);
+
+  return <Loading />;
+};
+
+export default ForcePasswordChangePage;

web/src/services/routing/index.tsx

@@ -22,6 +22,9 @@ const LoginPage = lazy(() => import("@reearth/classic/components/pages/Authentic
 const PasswordResetPage = lazy(
   () => import("@reearth/classic/components/pages/Authentication/PasswordReset"),
 );
+const ForcePasswordChangePage = lazy(
+  () => import("@reearth/classic/components/pages/Authentication/ForcePasswordChange"),
+);
 
 const SignupPage = lazy(
   () => import("@reearth/classic/components/pages/Authentication/SignupPage"),
@@ -57,6 +60,10 @@ export const AppRoutes = () => {
       index: true,
       element: <RootPage />,
     },
+    {
+      path: "auth/force-password-change",
+      element: <ForcePasswordChangePage />,
+    },
     {
       path: "auth/*",
       element: <RootPage />,