Allow Vue nodes to have their colors changed from selection toolbox (#5720)

## Summary

Fixes https://github.com/Comfy-Org/ComfyUI_frontend/issues/5680 by
allowing Vue nodes to properly synchronize color changes with LiteGraph
nodes, implementing header darkening and light theme adjustments.

<img width="2496" height="1512" alt="Screenshot from 2025-09-21
20-00-36"
src="https://github.com/user-attachments/assets/e3bdf645-1e0b-4d11-9ae5-9401f43e8e96"
/>

## Changes

- **What**: Implemented color property synchronization between LiteGraph
and Vue node rendering systems
- **Core Fix**: Added `nodeData.color` and `nodeData.bgcolor` to [v-memo
dependencies](https://vuejs.org/api/built-in-directives.html#v-memo) to
trigger re-renders on color changes
- **Color Logic**: Added header darkening using [memoized color
adjustments](https://github.com/Comfy-Org/ComfyUI_frontend/blob/main/src/utils/colorUtil.ts)
to match LiteGraph's ColorOption system
- **Event System**: Enhanced property change instrumentation in
LGraphNode.setColorOption to emit color/bgcolor events

## Review Focus

Vue component reactivity timing - the v-memo fix was critical for
immediate color updates. Verify light theme color adjustments match the
drawNode monkey patch behavior in app.ts.

## Technical Details

```mermaid
graph TD
    A[User Sets Color] --> B[LGraphNode.setColorOption]
    B --> C[Sets node.color & node.bgcolor]
    C --> D[Triggers property:changed events]
    D --> E[Vue Node Manager Updates]
    E --> F[v-memo Detects Change]
    F --> G[NodeHeader Re-renders]
    G --> H[Header Darkening Applied]

    style A fill:#f9f9f9,stroke:#333,color:#000
    style H fill:#f9f9f9,stroke:#333,color:#000
```

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-5720-Allow-Vue-nodes-to-have-their-colors-changed-from-selection-toolbox-2766d73d36508123b441d126a74a54b2)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Myestery <Myestery@users.noreply.github.com>
Co-authored-by: DrJKL <DrJKL@users.noreply.github.com>
Co-authored-by: github-actions <github-actions@github.com>

src/composables/graph/useGraphNodeManager.ts

@@ -41,6 +41,8 @@ export interface VueNodeData {
     collapsed?: boolean
     pinned?: boolean
   }
+  color?: string
+  bgcolor?: string
 }
 
 export interface GraphNodeManager {
@@ -126,7 +128,9 @@ export function useGraphNodeManager(graph: LGraph): GraphNodeManager {
       widgets: safeWidgets,
       inputs: node.inputs ? [...node.inputs] : undefined,
       outputs: node.outputs ? [...node.outputs] : undefined,
-      flags: node.flags ? { ...node.flags } : undefined
+      flags: node.flags ? { ...node.flags } : undefined,
+      color: node.color || undefined,
+      bgcolor: node.bgcolor || undefined
     }
   }
 
@@ -449,6 +453,24 @@ export function useGraphNodeManager(graph: LGraph): GraphNodeManager {
                 ...currentData,
                 mode: typeof event.newValue === 'number' ? event.newValue : 0
               })
+              break
+            case 'color':
+              vueNodeData.set(nodeId, {
+                ...currentData,
+                color:
+                  typeof event.newValue === 'string'
+                    ? event.newValue
+                    : undefined
+              })
+              break
+            case 'bgcolor':
+              vueNodeData.set(nodeId, {
+                ...currentData,
+                bgcolor:
+                  typeof event.newValue === 'string'
+                    ? event.newValue
+                    : undefined
+              })
           }
         }
       } else if (