[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/services/load3dService.ts

@@ -1,8 +1,8 @@
-import type { LGraphNode } from '@comfyorg/litegraph'
 import { toRaw } from 'vue'
 
 import Load3d from '@/extensions/core/load3d/Load3d'
 import Load3dAnimation from '@/extensions/core/load3d/Load3dAnimation'
+import type { LGraphNode } from '@/lib/litegraph/src/litegraph'
 import type { CustomInputSpec } from '@/schemas/nodeDef/nodeDefSchemaV2'
 
 type Load3dReadyCallback = (load3d: Load3d | Load3dAnimation) => void