feat(auth): add role/permission management (backend + frontend)

- RoleService: CRUD, assign_permissions, get_role_permissions
- PermissionService: list all tenant permissions
- Role handlers: 8 endpoints with RBAC permission checks
- Frontend Roles page: table, create/edit modal, permission assignment
- Frontend Roles API: full CRUD + permission operations
- Routes registered in AuthModule protected_routes

crates/erp-auth/src/module.rs

@@ -5,7 +5,7 @@ use erp_core::error::AppResult;
 use erp_core::events::EventBus;
 use erp_core::module::ErpModule;
 
-use crate::handler::{auth_handler, user_handler};
+use crate::handler::{auth_handler, role_handler, user_handler};
 
 /// Auth module implementing the `ErpModule` trait.
 ///
@@ -53,6 +53,25 @@ impl AuthModule {
                     .put(user_handler::update_user)
                     .delete(user_handler::delete_user),
             )
+            .route(
+                "/roles",
+                axum::routing::get(role_handler::list_roles).post(role_handler::create_role),
+            )
+            .route(
+                "/roles/{id}",
+                axum::routing::get(role_handler::get_role)
+                    .put(role_handler::update_role)
+                    .delete(role_handler::delete_role),
+            )
+            .route(
+                "/roles/{id}/permissions",
+                axum::routing::get(role_handler::get_role_permissions)
+                    .post(role_handler::assign_permissions),
+            )
+            .route(
+                "/permissions",
+                axum::routing::get(role_handler::list_permissions),
+            )
     }
 }