feat: support dev-only nodes (#8359)

## Summary

Support `dev_only` property to node definitions that hides nodes from
search and menus unless dev mode is enabled. Dev-only nodes display a
"DEV" badge when visible.

This functionality is primarily intended to support unit-testing nodes
on Comfy Cloud, but also has other uses.

## Changes

- **What**: Nodes flagged as dev_only in the node schema will only
appear in search and menus if Dev Mode is on.

## Screenshots (if applicable)

With Dev Mode off:
<img width="2189" height="1003" alt="image"
src="https://github.com/user-attachments/assets/a08e1fd7-dca9-4ce1-9964-5f4f3b7b95ac"
/>

With Dev Mode on:
<img width="2201" height="1066" alt="image"
src="https://github.com/user-attachments/assets/7fe6cd1f-f774-4f48-b604-a528e286b584"
/>

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8359-feat-support-dev-only-nodes-2f66d73d36508102839ee7cd66a26129)
by [Unito](https://www.unito.io)

src/services/litegraphService.ts

@@ -261,7 +261,7 @@ export const useLitegraphService = () => {
       static comfyClass: string
       static override title: string
       static override category: string
-      static nodeData: ComfyNodeDefV1 & ComfyNodeDefV2
+      static override nodeData: ComfyNodeDefV1 & ComfyNodeDefV2
 
       _initialMinSize = { width: 1, height: 1 }
 
@@ -394,7 +394,7 @@ export const useLitegraphService = () => {
       static comfyClass: string
       static override title: string
       static override category: string
-      static nodeData: ComfyNodeDefV1 & ComfyNodeDefV2
+      static override nodeData: ComfyNodeDefV1 & ComfyNodeDefV2
 
       _initialMinSize = { width: 1, height: 1 }
 
@@ -496,6 +496,13 @@ export const useLitegraphService = () => {
     // because `registerNodeType` will overwrite the assignments.
     node.category = nodeDef.category
     node.title = nodeDef.display_name || nodeDef.name
+
+    // Set skip_list for dev-only nodes based on current DevMode setting
+    // This ensures nodes registered after initial load respect the current setting
+    if (nodeDef.dev_only) {
+      const settingStore = useSettingStore()
+      node.skip_list = !settingStore.get('Comfy.DevMode')
+    }
   }
 
   /**