[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/workflowStore.ts

@@ -1,8 +1,8 @@
-import type { LGraph, Subgraph } from '@comfyorg/litegraph'
 import _ from 'lodash'
 import { defineStore } from 'pinia'
 import { type Raw, computed, markRaw, ref, shallowRef, watch } from 'vue'
 
+import type { LGraph, Subgraph } from '@/lib/litegraph/src/litegraph'
 import { ComfyWorkflowJSON } from '@/schemas/comfyWorkflowSchema'
 import type { NodeId } from '@/schemas/comfyWorkflowSchema'
 import { api } from '@/scripts/api'