fix: redirect to original page after re-authentication (#1959)

* fix: redirect to original page after re-authentication

When a session expires, the current URL is now preserved as a query
parameter on the login page. After successful login (including MFA
flows), the user is redirected back to their original page instead of
always landing on /home.

* secure

---------

Co-authored-by: Julien Fontanet <julien.fontanet@isonoe.net>

apps/client/src/lib/app-route.ts

@@ -29,4 +29,20 @@ const APP_ROUTE = {
   },
 };
 
+export function getPostLoginRedirect(): string {
+  const params = new URLSearchParams(window.location.search);
+  const redirect = params.get("redirect");
+  if (redirect) {
+    try {
+      const resolved = new URL(redirect, window.location.origin);
+      if (resolved.origin === window.location.origin) {
+        return resolved.pathname + resolved.search + resolved.hash;
+      }
+    } catch {
+      // malformed URL, fall through to default
+    }
+  }
+  return APP_ROUTE.HOME;
+}
+
 export default APP_ROUTE;