V2 Node Search (+ hidden Node Library changes) (#8987)

## Summary

Redesigned node search with categories

## Changes

- **What**: Adds a v2 search component, leaving the existing
implementation untouched
- It also brings onboard the incomplete node library & preview changes,
disabled and behind a hidden setting
- **Breaking**: Changes the 'default' value of the node search setting
to v2, adding v1 (legacy) as an option

## Screenshots (if applicable)




https://github.com/user-attachments/assets/2ab797df-58f0-48e8-8b20-2a1809e3735f

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8987-V2-Node-Search-hidden-Node-Library-changes-30c6d73d36508160902bcb92553f147c)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Yourz <crazilou@vip.qq.com>
Co-authored-by: Amp <amp@ampcode.com>
Co-authored-by: github-actions <github-actions@github.com>
Co-authored-by: GitHub Action <action@github.com>
Co-authored-by: Christian Byrne <cbyrne@comfy.org>

src/scripts/api.ts

@@ -243,6 +243,7 @@ export type GlobalSubgraphData = {
     search_aliases?: string[]
   }
   data: string | Promise<string>
+  essentials_category?: string
 }
 
 function addHeaderEntry(headers: HeadersInit, key: string, value: string) {