refactor: Reorganize layout system into new renderer architecture (#5071)

- Move layout system to renderer/core/layout/
  - Store, operations, adapters, and sync modules organized clearly
  - Merged layoutTypes.ts and layoutOperations.ts into single types.ts
- Move canvas rendering to renderer/core/canvas/
  - LiteGraph-specific code in litegraph/ subdirectory
  - PathRenderer at canvas level
- Move spatial indexing to renderer/core/spatial/
- Move Vue node composables to renderer/extensions/vue-nodes/
- Update all import paths throughout codebase
- Apply consistent naming (renderer vs rendering)

This establishes clearer separation between core rendering concerns
and optional extensions, making the architecture more maintainable.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-authored-by: Claude <noreply@anthropic.com>

tests-ui/tests/stores/layoutStore.test.ts

@@ -1,7 +1,7 @@
 import { beforeEach, describe, expect, it } from 'vitest'
 
-import { layoutStore } from '@/stores/layoutStore'
-import type { NodeLayout } from '@/types/layoutTypes'
+import { layoutStore } from '@/renderer/core/layout/store/LayoutStore'
+import type { NodeLayout } from '@/renderer/core/layout/types'
 
 describe('layoutStore CRDT operations', () => {
   beforeEach(() => {