UI - Redirect on invalid URL parameter to /software/add/fleet-maintained/:id (#24637)

## #24636

Redirect when NaN "foobar" provided as software id in url:

https://github.com/user-attachments/assets/e1b0ce3d-f494-447c-a452-285f0e6758af

- [x] Changes file added for user-visible changes in `changes/`,
- [x] Manual QA for all new/changed functionality

---------

Co-authored-by: Jacob Shandling <jacob@fleetdm.com>

changes/24636-UI-redirect-for-invalid-url-param

@@ -0,0 +1 @@
+* Redirect when user provides an invalid URL param for fleet-maintained software id

frontend/pages/SoftwarePage/SoftwareAddPage/SoftwareFleetMaintained/FleetMaintainedAppDetailsPage/FleetMaintainedAppDetailsPage.tsx

@@ -98,6 +98,9 @@ const FleetMaintainedAppDetailsPage = ({
 }: IFleetMaintainedAppDetailsPageProps) => {
   const teamId = location.query.team_id;
   const appId = parseInt(routeParams.id, 10);
+  if (isNaN(appId)) {
+    router.push(PATHS.SOFTWARE_ADD_FLEET_MAINTAINED);
+  }
 
   const { renderFlash } = useContext(NotificationContext);
   const { isPremiumTier } = useContext(AppContext);