[refactor] Migrate litegraph imports from npm package to local subtree

- Updated all imports from '@comfyorg/litegraph' to '@/lib/litegraph/src/'
- Replaced deep dist imports with direct source paths
- Updated CSS import in main.ts
- All imports now use the @ alias consistently

src/components/graph/widgets/TextPreviewWidget.vue

@@ -12,10 +12,10 @@
 </template>
 
 <script setup lang="ts">
-import { NodeId } from '@comfyorg/litegraph'
 import Skeleton from 'primevue/skeleton'
 import { computed, onMounted, ref, watch } from 'vue'
 
+import { NodeId } from '@/lib/litegraph/src/litegraph'
 import { useExecutionStore } from '@/stores/executionStore'
 import { linkifyHtml, nl2br } from '@/utils/formatUtil'