Phase 1 (additive, doesn't touch existing checks):
- Gate::before grants everything to holders of 'manage all' (the Admin role),
robustly (returns true/null, never false; swallows missing-permission).
- New RolePermissionManager Livewire component + view at /admin/permissions:
editable Roles x Permissions matrix (toggle saves instantly), create/delete
roles, create/delete permissions. Admin role and 'manage all' are protected.
- Link to the screen from /admin/users header.
Roles are editable from the UI as chosen.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
