Remove unused vue-sweetalert2 plugin

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RaRBJFZKSTA7naHGuQHfnQ

src/main.ts

@@ -20,7 +20,6 @@ import cytoscape from "cytoscape";
 import dagre from "cytoscape-dagre";
 import popper from "cytoscape-popper";
 import draggable from "vuedraggable";
-import VueSweetalert2 from "vue-sweetalert2";
 
 // import CSS
 import "./assets/main.css";
@@ -67,7 +66,6 @@ cytoscape.use(popper((ref) => ref));
 
 app.use(pinia);
 app.use(router);
-app.use(VueSweetalert2);
 app.use(ToastPlugin, {
   // use `this.$toast` in Vue.js
   position: "bottom",