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/components/sidebar/tabs/nodeLibrary/CustomNodesPanel.vue

@@ -0,0 +1,63 @@
+<template>
+  <TabsContent value="custom" class="flex-1 flex flex-col h-full">
+    <div
+      v-for="(section, index) in sections"
+      :key="section.title ?? index"
+      class="flex-1 overflow-y-auto h-full"
+    >
+      <!-- Section header -->
+      <h3
+        v-if="section.title"
+        class="px-4 py-2 text-xs font-medium tracking-wide text-muted-foreground mb-0"
+      >
+        {{ section.title }}
+      </h3>
+      <!-- Section tree -->
+      <TreeExplorerV2
+        v-model:expanded-keys="expandedKeys"
+        :root="section.root"
+        :show-context-menu="false"
+        @node-click="(node) => emit('nodeClick', node)"
+      />
+    </div>
+    <div class="flex-none py-3 border-t border-border-default text-center">
+      <Button
+        variant="secondary"
+        class="justify-start gap-3"
+        @click="handleOpenManager"
+      >
+        <i class="icon-[lucide--blocks] size-5 text-muted-foreground" />
+        {{ $t('g.manageExtensions') }}
+      </Button>
+    </div>
+  </TabsContent>
+</template>
+
+<script setup lang="ts">
+import { TabsContent } from 'reka-ui'
+
+import TreeExplorerV2 from '@/components/common/TreeExplorerV2.vue'
+import Button from '@/components/ui/button/Button.vue'
+import type { ComfyNodeDefImpl } from '@/stores/nodeDefStore'
+import type {
+  NodeLibrarySection,
+  RenderedTreeExplorerNode
+} from '@/types/treeExplorerTypes'
+import { useManagerState } from '@/workbench/extensions/manager/composables/useManagerState'
+
+defineProps<{
+  sections: NodeLibrarySection[]
+}>()
+
+const expandedKeys = defineModel<string[]>('expandedKeys', { required: true })
+
+const emit = defineEmits<{
+  nodeClick: [node: RenderedTreeExplorerNode<ComfyNodeDefImpl>]
+}>()
+
+const managerState = useManagerState()
+
+async function handleOpenManager() {
+  await managerState.openManager()
+}
+</script>