[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/element/useAbsolutePosition.ts

@@ -1,7 +1,7 @@
-import type { Size, Vector2 } from '@comfyorg/litegraph'
 import { CSSProperties, ref, watch } from 'vue'
 
 import { useCanvasPositionConversion } from '@/composables/element/useCanvasPositionConversion'
+import type { Size, Vector2 } from '@/lib/litegraph/src/litegraph'
 import { useCanvasStore } from '@/stores/graphStore'
 import { useSettingStore } from '@/stores/settingStore'