refactor(users)!: merge users.edit and users.delete into users.manage permission

BREAKING CHANGE: permissions `users.edit` and `users.delete` have been replaced by a single `users.manage` permission; any role or code referencing the old keys must be updated

- remove `USERS_EDIT` and `USERS_DELETE` from `PERMISSIONS` and `PERMISSION_DEFINITIONS`
- add `USERS_MANAGE` permission covering create, edit and delete actions
- update `db.js` to use `users.manage` in permission checks
- update `auth/api.js` to reference the new permission key
- update `UsersPage.client.js` to check `users.manage` instead of old keys
- update `api/define.js` and all README examples to reflect the new key

src/features/admin/pages/UsersPage.client.js

@@ -174,7 +174,7 @@ const UsersPageClient = ({ currentUserId, refreshKey, canEdit }) => {
 const UsersPage = ({ user }) => {
     const [createModalOpen, setCreateModalOpen] = useState(false);
     const [refreshKey, setRefreshKey] = useState(0);
-    const canEdit = user?.permissions?.includes('users.edit');
+    const canEdit = user?.permissions?.includes('users.manage');
 
     return (
         <div className="flex flex-col gap-4 sm:gap-6 lg:gap-8">