- Introduce a comprehensive permission system for subusers, including permission nodes and types with support for vehicles, bookings, orders, subusers, and self-serve modules.
- Implement `subusers_user`, `subuser_user_grant`, and `subusers_permission_node` classes for managing subuser permissions and grants.
- Extend `subuser_grants_o` with methods to retrieve permissions for subusers linked to customers.
- Add traits and enumerations to streamline permission handling across modules.
- Update subuser session handling to include token-based subuser lookups.