[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/services/colorPaletteService.ts

@@ -1,9 +1,9 @@
-import { LGraphCanvas } from '@comfyorg/litegraph'
-import { LiteGraph } from '@comfyorg/litegraph'
 import { toRaw } from 'vue'
 import { fromZodError } from 'zod-validation-error'
 
 import { useErrorHandling } from '@/composables/useErrorHandling'
+import { LGraphCanvas } from '@/lib/litegraph/src/litegraph'
+import { LiteGraph } from '@/lib/litegraph/src/litegraph'
 import {
   Colors,
   type Palette,