[refactor] Improve renderer domain organization (#5552)

* [refactor] Improve renderer architecture organization

Building on PR #5388, this refines the renderer domain structure:

**Key improvements:**
- Group all transform utilities in `transform/` subdirectory for better cohesion
- Move canvas state to dedicated `renderer/core/canvas/` domain
- Consolidate coordinate system logic (TransformPane, useTransformState, sync utilities)

**File organization:**
- `renderer/core/canvas/canvasStore.ts` (was `stores/graphStore.ts`)
- `renderer/core/layout/transform/` contains all coordinate system utilities
- Transform sync utilities co-located with core transform logic

This creates clearer domain boundaries and groups related functionality
while building on the foundation established in PR #5388.

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

Co-Authored-By: Claude <noreply@anthropic.com>

* fix: Clean up linter-modified files

* Fix import paths and clean up unused imports after rebase

- Update all remaining @/stores/graphStore references to @/renderer/core/canvas/canvasStore
- Remove unused imports from selection toolbox components
- All tests pass, only reka-ui upstream issue remains in typecheck

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

Co-Authored-By: Claude <noreply@anthropic.com>

* [auto-fix] Apply ESLint and Prettier fixes

---------

Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: GitHub Action <action@github.com>

src/composables/canvas/useCanvasTransformSync.ts

@@ -1,7 +1,7 @@
 import { onUnmounted, ref } from 'vue'
 
 import { LGraphCanvas } from '@/lib/litegraph/src/litegraph'
-import { useCanvasStore } from '@/stores/graphStore'
+import { useCanvasStore } from '@/renderer/core/canvas/canvasStore'
 
 interface CanvasTransformSyncOptions {
   /**

src/composables/canvas/useSelectedLiteGraphItems.ts

@@ -4,8 +4,8 @@ import {
   Positionable,
   Reroute
 } from '@/lib/litegraph/src/litegraph'
+import { useCanvasStore } from '@/renderer/core/canvas/canvasStore'
 import { app } from '@/scripts/app'
-import { useCanvasStore } from '@/stores/graphStore'
 import {
   collectFromNodes,
   traverseNodesDepthFirst

src/composables/canvas/useSelectionToolboxPosition.ts

@@ -6,8 +6,8 @@ import { useSelectedLiteGraphItems } from '@/composables/canvas/useSelectedLiteG
 import { useVueFeatureFlags } from '@/composables/useVueFeatureFlags'
 import type { ReadOnlyRect } from '@/lib/litegraph/src/interfaces'
 import { LGraphNode } from '@/lib/litegraph/src/litegraph'
+import { useCanvasStore } from '@/renderer/core/canvas/canvasStore'
 import { layoutStore } from '@/renderer/core/layout/store/layoutStore'
-import { useCanvasStore } from '@/stores/graphStore'
 import { isLGraphGroup, isLGraphNode } from '@/utils/litegraphUtil'
 import { computeUnionBounds } from '@/utils/mathUtil'