Add new Role-change refresh banner

When an admin changes a logged-in user's role (e.g. promotes staff to Manager, or demotes them), the backend already enforces the new role immediately on every request, but the frontend UI keeps showing the old role/permissions until the page is reloaded. Add a lightweight, non-intrusive top banner that appears when the server's current role for the signed-in user no longer matches the role their session/UI is using, prompting them to refresh

When an admin changes a logged-in user's role (e.g. promotes staff to Manager, or demotes them), the backend already enforces the new role immediately on every request, but the frontend UI keeps showing the old role/permissions until the page is reloaded. Add a lightweight, non-intrusive top banner that appears when the server's current role for the signed-in user no longer matches the role their session/UI is using, prompting them to refresh