feat: add skeleton visualization toggle for 3D models (#7857)

## Summary

For better support animation 3d model custon node, such as
https://github.com/jtydhr88/ComfyUI-HY-Motion1, add ability to show/hide
skeleton bones in Load3D nodes for models with skeletal animation. Uses
THREE.SkeletonHelper with root bone detection to properly support both
FBX and GLB model formats.

## Screenshots


https://github.com/user-attachments/assets/df9de4a6-549e-4227-aa00-8859d71f43d1

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-7857-feat-add-skeleton-visualization-toggle-for-3D-models-2e06d73d365081a39f49f81f72657a70)
by [Unito](https://www.unito.io)

src/components/load3d/Load3D.vue

@@ -24,6 +24,7 @@
         v-model:light-config="lightConfig"
         :is-splat-model="isSplatModel"
         :is-ply-model="isPlyModel"
+        :has-skeleton="hasSkeleton"
         @update-background-image="handleBackgroundImageUpdate"
         @export-model="handleExportModel"
       />
@@ -116,6 +117,7 @@ const {
   isPreview,
   isSplatModel,
   isPlyModel,
+  hasSkeleton,
   hasRecording,
   recordingDuration,
   animations,

src/components/load3d/Load3DControls.vue

@@ -58,8 +58,10 @@
         v-if="showModelControls"
         v-model:material-mode="modelConfig!.materialMode"
         v-model:up-direction="modelConfig!.upDirection"
+        v-model:show-skeleton="modelConfig!.showSkeleton"
         :hide-material-mode="isSplatModel"
         :is-ply-model="isPlyModel"
+        :has-skeleton="hasSkeleton"
       />
 
       <CameraControls
@@ -99,9 +101,14 @@ import type {
 } from '@/extensions/core/load3d/interfaces'
 import { cn } from '@/utils/tailwindUtil'
 
-const { isSplatModel = false, isPlyModel = false } = defineProps<{
+const {
+  isSplatModel = false,
+  isPlyModel = false,
+  hasSkeleton = false
+} = defineProps<{
   isSplatModel?: boolean
   isPlyModel?: boolean
+  hasSkeleton?: boolean
 }>()
 
 const sceneConfig = defineModel<SceneConfig>('sceneConfig')

src/components/load3d/controls/ModelControls.vue

@@ -70,6 +70,22 @@
         </div>
       </div>
     </div>
+
+    <div v-if="hasSkeleton">
+      <Button
+        v-tooltip.right="{
+          value: t('load3d.showSkeleton'),
+          showDelay: 300
+        }"
+        size="icon"
+        variant="textonly"
+        :class="cn('rounded-full', showSkeleton && 'bg-blue-500')"
+        :aria-label="t('load3d.showSkeleton')"
+        @click="showSkeleton = !showSkeleton"
+      >
+        <i class="pi pi-sitemap text-lg text-white" />
+      </Button>
+    </div>
   </div>
 </template>
 
@@ -84,13 +100,19 @@ import type {
 import { t } from '@/i18n'
 import { cn } from '@/utils/tailwindUtil'
 
-const { hideMaterialMode = false, isPlyModel = false } = defineProps<{
+const {
+  hideMaterialMode = false,
+  isPlyModel = false,
+  hasSkeleton = false
+} = defineProps<{
   hideMaterialMode?: boolean
   isPlyModel?: boolean
+  hasSkeleton?: boolean
 }>()
 
 const materialMode = defineModel<MaterialMode>('materialMode')
 const upDirection = defineModel<UpDirection>('upDirection')
+const showSkeleton = defineModel<boolean>('showSkeleton')
 
 const showUpDirection = ref(false)
 const showMaterialMode = ref(false)