Implement role and user management enhancements

- Added MaxIpLimit to roles, allowing for the configuration of simultaneous IP limits for users.
- Updated role creation and update commands to include MaxIpLimit, ensuring proper handling in the application logic.
- Enhanced user management by introducing a DELETE endpoint for user accounts, with appropriate checks to prevent self-deletion.
- Updated documentation to reflect changes in role and user management, clarifying the new IP limit functionality and user deletion process.
- Adjusted related tests to cover new functionality and ensure robust validation of role and user management features.

frontend/src/routes/admin/roles.tsx

@@ -51,6 +51,7 @@ function AdminRolesPage() {
             <tr className="border-b border-border text-muted-foreground">
               <th className="py-2 font-medium">{t('admin.roles.name')}</th>
               <th className="py-2 font-medium">{t('admin.roles.maxConfigs')}</th>
+              <th className="py-2 font-medium">{t('admin.roles.maxIpLimit')}</th>
               <th className="py-2" />
               <th className="py-2" />
             </tr>
@@ -62,6 +63,7 @@ function AdminRolesPage() {
                   {role.name} {role.isSystem && <Badge variant="outline">{t('admin.roles.system')}</Badge>}
                 </td>
                 <td className="py-2">{role.maxConfigs < 0 ? t('unlimited') : role.maxConfigs}</td>
+                <td className="py-2">{role.maxIpLimit < 0 ? t('unlimited') : role.maxIpLimit}</td>
                 <td className="py-2 text-right">
                   <Button size="sm" variant="outline" onClick={() => setEditing(role)}>
                     {t('admin.roles.edit')}