[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

tests-ui/tests/utils/graphTraversalUtil.test.ts

@@ -1,6 +1,10 @@
-import type { LGraph, LGraphNode, Subgraph } from '@comfyorg/litegraph'
 import { describe, expect, it, vi } from 'vitest'
 
+import type {
+  LGraph,
+  LGraphNode,
+  Subgraph
+} from '@/lib/litegraph/src/litegraph'
 import {
   collectAllNodes,
   collectFromNodes,