feat(roles): role CRUD screen (list + form name/description + view/edit/delete + bulk)

Per request:
- Migration: add nullable 'description' to the roles table.
- RoleManager Livewire component + view at /admin/roles:
  * Roles list table with per-row checkboxes for bulk selection (+ select-all)
    and a 'Delete selected' bulk action (protected roles skipped).
  * 'New role' opens a modal form with just Name + Description (and permission
    checkboxes to assign).
  * Per-row View / Edit / Delete buttons (View modal shows description,
    counts and assigned permissions).
- Admin role stays protected (no rename/delete/lose 'manage all').
- /admin/users links to the new Roles screen; the phase-1 permission matrix
  stays available via a 'Matrix view' link.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

resources/views/admin/users.blade.php

@@ -6,8 +6,8 @@
             </h2>
             
             <div class="flex items-center gap-2">
-                <a href="{{ route('admin.permissions') }}" class="btn btn-outline btn-sm gap-1" wire:navigate>
-                    <x-heroicon-o-shield-check class="w-4 h-4" /> {{ __('Permissions') }}
+                <a href="{{ route('admin.roles') }}" class="btn btn-outline btn-sm gap-1" wire:navigate>
+                    <x-heroicon-o-shield-check class="w-4 h-4" /> {{ __('Roles & permissions') }}
                 </a>
                 <a href="{{ route('admin.users.create') }}" class="btn btn-primary btn-sm gap-1" wire:navigate>
                     <x-heroicon-o-plus class="w-4 h-4" /> {{ __('New user') }}