fix: delete button visible pour tous les templates (grise si systeme)

frontend/src/pages/CausalLab.tsx

@@ -442,13 +442,16 @@ function TabLibrary() {
                 <span className="text-xs px-2 py-1 rounded bg-purple-900/30 text-purple-300 border border-purple-700/40">
                   v{selected.heuristic_ver}
                 </span>
-                {selected.created_by !== 'system' && (
-                  <button onClick={deleteTemplate} disabled={deleting}
-                    title="Supprimer ce template"
-                    className="p-1 rounded hover:bg-red-900/30 text-slate-500 hover:text-red-400 transition-colors disabled:opacity-40">
-                    <Trash2 className="w-3.5 h-3.5" />
-                  </button>
-                )}
+                <button
+                  onClick={selected.created_by !== 'system' ? deleteTemplate : undefined}
+                  disabled={deleting || selected.created_by === 'system'}
+                  title={selected.created_by === 'system' ? 'Template système — non supprimable' : 'Supprimer ce template'}
+                  className={clsx('p-1 rounded transition-colors',
+                    selected.created_by === 'system'
+                      ? 'text-slate-700 cursor-not-allowed'
+                      : 'text-slate-500 hover:bg-red-900/30 hover:text-red-400 disabled:opacity-40')}>
+                  <Trash2 className="w-3.5 h-3.5" />
+                </button>
               </div>
             </div>
             {selected.ai_rationale && (