feat: App mode - Switch to Nodes 2.0 when entering builder (#10337)

## Summary

We've had some reports of issues selecting inputs/nodes when trying to
use the builder in LiteGraph mode and due to the complexity of the
canvas system, we're going to enable Nodes 2.0 when entering the builder
to ensure the best experience.

## Changes

- **What**:  
- When entering builder select mode automatically switch to Nodes 2.0
- Extract reusable component from features toast
- Show popup telling user the mode was changed
- Add hidden setting for storing "don't show again" on the switch popup

## Review Focus
- I have not removed the LiteGraph selection code in case someone still
manages to enter the builder in LiteGraph mode, this should be cleaned
up in future

## Screenshots (if applicable)

<img width="423" height="224" alt="image"
src="https://github.com/user-attachments/assets/cc2591bc-e5dc-47ef-a3c6-91ca7b6066ff"
/>

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-10337-feat-App-mode-Switch-to-Nodes-2-0-when-entering-builder-3296d73d3650818e9f3cdaac59d15609)
by [Unito](https://www.unito.io)

browser_tests/fixtures/utils/litegraphUtils.ts

@@ -281,6 +281,14 @@ export class NodeReference {
   getType(): Promise<string> {
     return this.getProperty('type')
   }
+  async centerOnNode(): Promise<void> {
+    await this.comfyPage.page.evaluate((id) => {
+      const node = window.app!.canvas.graph!.getNodeById(id)
+      if (!node) throw new Error(`Node ${id} not found`)
+      window.app!.canvas.centerOnNode(node)
+    }, this.id)
+    await this.comfyPage.nextFrame()
+  }
   async getPosition(): Promise<Position> {
     const pos = await this.comfyPage.canvasOps.convertOffsetToCanvas(
       await this.getProperty<[number, number]>('pos')