[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/composables/useLitegraphSettings.ts

@@ -1,6 +1,10 @@
-import { CanvasPointer, LGraphNode, LiteGraph } from '@comfyorg/litegraph'
 import { watchEffect } from 'vue'
 
+import {
+  CanvasPointer,
+  LGraphNode,
+  LiteGraph
+} from '@/lib/litegraph/src/litegraph'
 import { useCanvasStore } from '@/stores/graphStore'
 import { useSettingStore } from '@/stores/settingStore'