style(workspace): style '+ Notiz' button in sidebar matching 'Neue Liste' dashed style

frontend/src/features/workspace/WorkspaceView.tsx

@@ -951,7 +951,8 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
               <button
                 type="button"
                 onClick={() => handleCreateDocument('')}
-                className="btn-primary inline-flex items-center gap-1 px-2 py-1 text-xs font-semibold"
+                className="h-7 px-2.5 bg-canvas hover:bg-panel border border-border border-dashed rounded-btn text-xs text-muted hover:text-main inline-flex items-center gap-1 transition-colors cursor-pointer"
+                title="Neue Notiz anlegen"
               >
                 <Plus className="w-3.5 h-3.5" />
                 <span>Notiz</span>