Slot functionality for vue nodes (#5628)

Allows for simple slot functionality in vue nodes mode.

Has:
- Drag new link from slot
- Connect new link from dropping on slot

Now:
- Tests

After:
- Drop on reroute
- Correct link color on connect
- Drop on node
- Hover effects

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-5628-Slot-functionality-for-vue-nodes-2716d73d365081c59a3cef7c8a5e539e)
by [Unito](https://www.unito.io)

---------

Co-authored-by: bymyself <cbyrne@comfy.org>
Co-authored-by: AustinMroz <austin@comfy.org>
Co-authored-by: Claude <noreply@anthropic.com>

src/components/graph/GraphCanvas.vue

@@ -117,6 +117,7 @@ import { useWorkflowAutoSave } from '@/platform/workflow/persistence/composables
 import { useWorkflowPersistence } from '@/platform/workflow/persistence/composables/useWorkflowPersistence'
 import { useCanvasStore } from '@/renderer/core/canvas/canvasStore'
 import { SelectedNodeIdsKey } from '@/renderer/core/canvas/injectionKeys'
+import { attachSlotLinkPreviewRenderer } from '@/renderer/core/canvas/links/slotLinkPreviewRenderer'
 import { useCanvasInteractions } from '@/renderer/core/canvas/useCanvasInteractions'
 import TransformPane from '@/renderer/core/layout/transform/TransformPane.vue'
 import MiniMap from '@/renderer/extensions/minimap/MiniMap.vue'
@@ -404,6 +405,7 @@ onMounted(async () => {
 
   // @ts-expect-error fixme ts strict error
   await comfyApp.setup(canvasRef.value)
+  attachSlotLinkPreviewRenderer(comfyApp.canvas)
   canvasStore.canvas = comfyApp.canvas
   canvasStore.canvas.render_canvas_border = false
   workspaceStore.spinner = false