refactor: extract CONFIG/GET_CONFIG symbols to constants file

- Create src/lib/litegraph/constants.ts with CONFIG and GET_CONFIG symbols
- Update extension files to import from constants
- Re-export from litegraphService for backward compatibility

Part of Phase 1 circular dependency fixes.

Amp-Thread-ID: https://ampcode.com/threads/T-019bfe05-7da5-736f-bff0-34743c003b34
Co-authored-by: Amp <amp@ampcode.com>

src/extensions/core/widgetInputs.ts

@@ -19,7 +19,7 @@ import {
   addValueControlWidgets,
   isValidWidgetType
 } from '@/scripts/widgets'
-import { CONFIG, GET_CONFIG } from '@/services/litegraphService'
+import { CONFIG, GET_CONFIG } from '@/lib/litegraph/constants'
 import { mergeInputSpec } from '@/utils/nodeDefUtil'
 import { applyTextReplacements } from '@/utils/searchAndReplace'
 import { isPrimitiveNode } from '@/renderer/utils/nodeTypeGuards'

src/lib/litegraph/constants.ts

@@ -0,0 +1,14 @@
+/**
+ * Symbols used for widget configuration in litegraph nodes.
+ * Extracted to break circular dependencies between litegraphService and extensions.
+ */
+
+/**
+ * Symbol used to access the config object on a widget.
+ */
+export const CONFIG = Symbol('CONFIG')
+
+/**
+ * Symbol used to access the config getter function on a widget.
+ */
+export const GET_CONFIG = Symbol('GET_CONFIG')

src/services/litegraphService.ts

@@ -1,5 +1,7 @@
 import _ from 'es-toolkit/compat'
 
+import { CONFIG, GET_CONFIG } from '@/lib/litegraph/constants'
+export { CONFIG, GET_CONFIG }
 import { downloadFile } from '@/base/common/downloadUtil'
 import { useSelectedLiteGraphItems } from '@/composables/canvas/useSelectedLiteGraphItems'
 import { useSubgraphOperations } from '@/composables/graph/useSubgraphOperations'
@@ -68,9 +70,6 @@ export interface HasInitialMinSize {
   _initialMinSize: { width: number; height: number }
 }
 
-export const CONFIG = Symbol()
-export const GET_CONFIG = Symbol()
-
 /**
  * Service that augments litegraph with ComfyUI specific functionality.
  */