Add freight demo data seeder and permissions management

- Introduced `DemoFreightDataSeeder` to seed demo freight data including wagons, approval rules, and staff users.
- Added `seed:freight-demo` script to `package.json` for easy execution.
- Updated permissions for operations officer and added permission checks in various components.
- Enhanced sidebar and booking actions to respect user permissions.

apps/edr-freight-web/backoffice/src/components/layout/types.ts

@@ -6,6 +6,8 @@ export interface SidebarItem {
   href?: string;
   icon?: ReactNode;
   children?: SidebarItem[];
+  /** Permission key(s) required to see this item; ANY grants access. */
+  permission?: string | string[];
 }
 
 export interface SidebarSection {