Fix links to wrong slots in vue mode (#6181)

Error is divided into 2 parts
- A widget lacking slotMetadata would create a slot overwriting the
index 0 slot
- Slot data wasn't reactive. Any dynamic widgets would not have
slotMetadata
<img width="1065" height="436" alt="image"
src="https://github.com/user-attachments/assets/c83b04fb-3b3a-4abb-8b68-99b305336348"
/>

See #5705
- Describes incorrect links internal to subgraphs. Likely a different,
already solved issue

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-6181-Fix-links-to-wrong-slots-in-vue-mode-2936d73d36508136ad43d8c818bf9fba)
by [Unito](https://www.unito.io)

src/renderer/extensions/vueNodes/components/NodeWidgets.vue

@@ -24,16 +24,17 @@
       <!-- Widget Input Slot Dot -->
 
       <div
-        class="z-10 opacity-0 transition-opacity duration-150 group-hover:opacity-100"
+        class="z-10 w-3 opacity-0 transition-opacity duration-150 group-hover:opacity-100"
       >
         <InputSlot
+          v-if="widget.slotMetadata"
           :slot-data="{
             name: widget.name,
             type: widget.type,
             boundingRect: [0, 0, 0, 0]
           }"
           :node-id="nodeData?.id != null ? String(nodeData.id) : ''"
-          :index="widget.slotMetadata?.index ?? 0"
+          :index="widget.slotMetadata.index"
           :dot-only="true"
         />
       </div>