[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/stores/subgraphNavigationStore.ts

@@ -1,9 +1,9 @@
 import QuickLRU from '@alloc/quick-lru'
-import type { Subgraph } from '@comfyorg/litegraph'
-import type { DragAndScaleState } from '@comfyorg/litegraph/dist/DragAndScale'
 import { defineStore } from 'pinia'
 import { computed, ref, shallowRef, watch } from 'vue'
 
+import type { DragAndScaleState } from '@/lib/litegraph/src/DragAndScale'
+import type { Subgraph } from '@/lib/litegraph/src/litegraph'
 import { app } from '@/scripts/app'
 import { findSubgraphPathById } from '@/utils/graphTraversalUtil'
 import { isNonNullish } from '@/utils/typeGuardUtil'