Add UI code for configuring subgraphNode widgets (#5826)

The third PR for managing display of widgets on subgraph nodes. This is
the one that actually makes the functionality usable and user visible.

Adds
- A right-side modal for configuring which widgets are promoted,
accessed by right click or selection toolbar
- This menu allows for re-arranging widget order by dragging and
dropping.
- Indicators inside the subgraph for which widgets have been promoted.
- Context menu options for promoting or demoting widget inside of a
subgraph.
<img width="767" height="694" alt="image"
src="https://github.com/user-attachments/assets/4f78645d-7b26-48ba-8c49-78f4807e89e8"
/>
<img width="784" height="435" alt="image"
src="https://github.com/user-attachments/assets/7005c730-a732-481e-befb-57019a8a31a7"
/>


Known issues
- Some preview widgets are not added to a node until a draw operation
occurs. The code does not yet have a way of determining which nodes
should have draw operations forced to facilitate initial widget
creation.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-5826-Add-UI-code-for-configuring-subgraphNode-widgets-27c6d73d36508146accbf395e5bcd36a)
by [Unito](https://www.unito.io)

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

@@ -332,7 +332,7 @@ const handleEnterSubgraph = () => {
     return
   }
 
-  canvas.openSubgraph(litegraphNode.subgraph)
+  canvas.openSubgraph(litegraphNode.subgraph, litegraphNode)
 }
 
 const nodeOutputs = useNodeOutputStore()

src/renderer/extensions/vueNodes/widgets/composables/useImagePreviewWidget.ts

@@ -19,7 +19,8 @@ import { is_all_same_aspect_ratio } from '@/utils/imageUtil'
 const renderPreview = (
   ctx: CanvasRenderingContext2D,
   node: LGraphNode,
-  shiftY: number
+  shiftY: number,
+  computedHeight: number | undefined
 ) => {
   const canvas = useCanvasStore().getCanvas()
   const mouse = canvas.graph_mouse
@@ -46,7 +47,7 @@ const renderPreview = (
   const allowImageSizeDraw = settingStore.get('Comfy.Node.AllowImageSizeDraw')
   const IMAGE_TEXT_SIZE_TEXT_HEIGHT = allowImageSizeDraw ? 15 : 0
   const dw = node.size[0]
-  const dh = node.size[1] - shiftY - IMAGE_TEXT_SIZE_TEXT_HEIGHT
+  const dh = computedHeight ? computedHeight - IMAGE_TEXT_SIZE_TEXT_HEIGHT : 0
 
   if (imageIndex == null) {
     // No image selected; draw thumbnails of all
@@ -260,7 +261,7 @@ class ImagePreviewWidget extends BaseWidget {
   }
 
   override drawWidget(ctx: CanvasRenderingContext2D): void {
-    renderPreview(ctx, this.node, this.y)
+    renderPreview(ctx, this.node, this.y, this.computedHeight)
   }
 
   override onPointerDown(pointer: CanvasPointer, node: LGraphNode): boolean {