refactor: eliminate unsafe type assertions from Group 2 test files (#8258)

## Summary
Improved type safety in test files by eliminating unsafe type assertions
and adopting official testing patterns. Reduced unsafe `as unknown as`
type assertions and eliminated all `null!` assertions.

## Changes
- **Adopted @pinia/testing patterns**
- Replaced manual Pinia store mocking with `createTestingPinia()` in
`useSelectionState.test.ts`
  - Eliminated ~120 lines of mock boilerplate
- Created `createMockSettingStore()` helper to replace duplicated store
mocks in `useCoreCommands.test.ts`

- **Eliminated unsafe null assertions**
- Created explicit `MockMaskEditorStore` interface with proper nullable
types in `useCanvasTools.test.ts`
- Replaced `null!` initializations with `null` and used `!` at point of
use or `?.` for optional chaining

- **Made partial mock intent explicit**
- Updated test utilities in `litegraphTestUtils.ts` to use explicit
`Partial<T>` typing
- Changed cast pattern from `as T` to `as Partial<T> as T` to show
incomplete mock intent
- Applied to `createMockLGraphNode()`, `createMockPositionable()`, and
`createMockLGraphGroup()`

- **Created centralized mock utilities** in
`src/utils/__tests__/litegraphTestUtils.ts`
- `createMockLGraphNode()`, `createMockPositionable()`,
`createMockLGraphGroup()`, `createMockSubgraphNode()`
  - Updated 8+ test files to use centralized utilities
- Used union types `Partial<T> | Record<string, unknown>` for flexible
mock creation

## Results
- ✅ 0 typecheck errors
- ✅ 0 lint errors  
- ✅ All tests passing in modified files
- ✅ Eliminated all `null!` assertions
- ✅ Reduced unsafe double-cast patterns significantly

## Files Modified (18)
- `src/components/graph/SelectionToolbox.test.ts`
-
`src/components/graph/selectionToolbox/{BypassButton,ColorPickerButton,ExecuteButton}.test.ts`
- `src/components/sidebar/tabs/queue/ResultGallery.test.ts`
- `src/composables/canvas/useSelectedLiteGraphItems.test.ts`
- `src/composables/graph/{useGraphHierarchy,useSelectionState}.test.ts`
-
`src/composables/maskeditor/{useCanvasHistory,useCanvasManager,useCanvasTools,useCanvasTransform}.test.ts`
- `src/composables/node/{useNodePricing,useWatchWidget}.test.ts`
- `src/composables/{useBrowserTabTitle,useCoreCommands}.test.ts`
- `src/utils/__tests__/litegraphTestUtils.ts`

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8258-refactor-eliminate-unsafe-type-assertions-from-Group-2-test-files-2f16d73d365081549c65fd546cc7c765)
by [Unito](https://www.unito.io)

---------

Co-authored-by: GitHub Action <action@github.com>
Co-authored-by: Alexander Brown <drjkl@comfy.org>
Co-authored-by: Amp <amp@ampcode.com>
Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>
Co-authored-by: AustinMroz <austin@comfy.org>
Co-authored-by: Christian Byrne <cbyrne@comfy.org>
Co-authored-by: Benjamin Lu <benjaminlu1107@gmail.com>

src/extensions/core/widgetInputs.ts

@@ -1,7 +1,4 @@
-import {
-  type CallbackParams,
-  useChainCallback
-} from '@/composables/functional/useChainCallback'
+import { useChainCallback } from '@/composables/functional/useChainCallback'
 import { LGraphNode, LiteGraph } from '@/lib/litegraph/src/litegraph'
 import type {
   INodeInputSlot,
@@ -11,7 +8,10 @@ import type {
 } from '@/lib/litegraph/src/litegraph'
 import { NodeSlot } from '@/lib/litegraph/src/node/NodeSlot'
 import type { CanvasPointerEvent } from '@/lib/litegraph/src/types/events'
-import type { IBaseWidget } from '@/lib/litegraph/src/types/widgets'
+import type {
+  IBaseWidget,
+  TWidgetValue
+} from '@/lib/litegraph/src/types/widgets'
 import type { InputSpec } from '@/schemas/nodeDefSchema'
 import { app } from '@/scripts/app'
 import {
@@ -26,7 +26,7 @@ import { isPrimitiveNode } from '@/renderer/utils/nodeTypeGuards'
 
 const replacePropertyName = 'Run widget replace on values'
 export class PrimitiveNode extends LGraphNode {
-  controlValues?: any[]
+  controlValues?: TWidgetValue[]
   lastType?: string
   static override category: string
   constructor(title: string) {
@@ -561,7 +561,7 @@ app.registerExtension({
     const origOnInputDblClick = nodeType.prototype.onInputDblClick
     nodeType.prototype.onInputDblClick = function (
       this: LGraphNode,
-      ...[slot, ...args]: CallbackParams<typeof origOnInputDblClick>
+      ...[slot, ...args]: Parameters<NonNullable<typeof origOnInputDblClick>>
     ) {
       const r = origOnInputDblClick?.apply(this, [slot, ...args])