Node ghost mode when adding nodes (#8694)

## Summary

Adds option for adding a node as a "ghost" that follows the cursor until
the user left clicks to confirm, or esc/right click to cancel.

## Changes

- **What**: 
Adds option for `ghost` when calling `graph.add`  
This adds the node with a `flag` of ghost which causes it to render
transparent
Selects the node, then sets the canvas as dragging to stick the node to
the cursor

## Screenshots (if applicable)



https://github.com/user-attachments/assets/dcb5702f-aba3-4983-aa40-c51f24a4767a

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8694-Node-ghost-mode-when-adding-nodes-2ff6d73d3650815591f2c28415050463)
by [Unito](https://www.unito.io)

src/composables/graph/useGraphNodeManager.ts

@@ -70,6 +70,7 @@ export interface VueNodeData {
   color?: string
   flags?: {
     collapsed?: boolean
+    ghost?: boolean
     pinned?: boolean
   }
   hasErrors?: boolean
@@ -526,6 +527,15 @@ export function useGraphNodeManager(graph: LGraph): GraphNodeManager {
                 }
               })
               break
+            case 'flags.ghost':
+              vueNodeData.set(nodeId, {
+                ...currentData,
+                flags: {
+                  ...currentData.flags,
+                  ghost: Boolean(propertyEvent.newValue)
+                }
+              })
+              break
             case 'flags.pinned':
               vueNodeData.set(nodeId, {
                 ...currentData,