Issue: RoleManager is a concrete struct, preventing custom RBAC implementations

Issue: RoleManager is a concrete struct, preventing custom RBAC implementations: a task in LegoFlow-SWE (Harbor dataset). Currently, the RoleManager type in casbin’s RBAC logic is a concrete struct, not an interface. This makes it impossible for users to substitute their own role manager…

The task

Currently, the `RoleManager` type in casbin’s RBAC logic is a concrete struct, not an interface. This makes it impossible for users to substitute their own role manager implementations when they need to integrate with external systems, databases, or custom hierarchy resolution logic. The existing `RoleManager`…

Part of Lego-X/LegoFlow-SWE.