[bug]: Add Permission and Role-Hierarchy Prechecks

### Problem
Role creation/assignment can fail silently when bot lacks `Manage Roles` or role hierarchy is lower than target role.

### Proposed Work
- Add explicit permission checks before create/remove/add role operations.
- Return clear message guiding server admins on missing permissions.

### Acceptance Criteria
- Commands detect and report missing permissions before attempting role mutations.
- No unhandled promise rejection from role operations.

No files or tests are named. Start by locating the commands that create, remove, or add roles and inspect their existing error handling; done means each role mutation checks Manage Roles and hierarchy first, reports a clear administrator-facing message, and produces no unhandled promise rejection.

Written by the indexing model from the issue text.