refactor(node-replacement): reorganize domain components and expand comprehensive test suite (#9301)

## Summary

Resolves six open issues by reorganizing node replacement components
into a domain-driven folder structure, refactoring event handling to
follow the emit pattern, and adding comprehensive test coverage across
all affected modules.

## Changes

- **What**:
- Moved `SwapNodeGroupRow.vue` and `SwapNodesCard.vue` from
`src/components/rightSidePanel/errors/` to
`src/platform/nodeReplacement/components/` (Issues #9255)
- Moved `useMissingNodeScan.ts` from `src/composables/` to
`src/platform/nodeReplacement/missingNodeScan.ts`, renamed to reflect it
is a plain function not a Vue composable (Issues #9254)
- Refactored `SwapNodeGroupRow.vue` to emit a `'replace'` event instead
of calling `useNodeReplacement()` and `useExecutionErrorStore()`
directly; replacement logic now handled in `TabErrors.vue` (Issue #9267)
- Added unit tests for `removeMissingNodesByType`
(`executionErrorStore.test.ts`), `scanMissingNodes`
(`missingNodeScan.test.ts`), and `swapNodeGroups` computed
(`swapNodeGroups.test.ts`, `useErrorGroups.test.ts`) (Issue #9270)
- Added placeholder detection tests covering unregistered-type detection
when `has_errors` is false, and exclusion of registered types
(`useNodeReplacement.test.ts`) (Issue #9271)
- Added component tests for `MissingNodeCard` and `MissingPackGroupRow`
covering rendering, expand/collapse, events, install states, and edge
cases (Issue #9231)
- Added component tests for `SwapNodeGroupRow` and `SwapNodesCard`
(Issues #9255, #9267)

## Additional Changes (Post-Review)

- **Edge case guard in placeholder detection**
(`useNodeReplacement.ts`): When `last_serialization.type` is absent (old
serialization format), the predicate falls back to `n.type`, which the
app may have already run through `sanitizeNodeName` — stripping HTML
special characters (`& < > " ' \` =`). In that case, a `Set.has()`
lookup against the original unsanitized type name would silently miss,
causing replacement to be skipped.

Fixed by including sanitized variants of each target type in the
`targetTypes` Set at construction time. For the overwhelmingly common
case (no special characters in type names), the Set deduplicates the
entries and runtime behavior is identical to before.

A regression test was added to cover the specific scenario:
`last_serialization.type` absent + live `n.type` already sanitized.

## Review Focus

- `TabErrors.vue`: confirm the new `@replace` event handler correctly
replaces nodes and removes them from missing nodes list (mirrors the old
inline logic in `SwapNodeGroupRow`)
- `missingNodeScan.ts`: filename/export name change from
`useMissingNodeScan` — verify all call sites updated via `app.ts`
- Test mocking strategy: module-level `vi.mock()` factories use closures
over `ref`/plain objects to allow per-test overrides without global
mutable state

- Fixes #9231
- Fixes #9254
- Fixes #9255
- Fixes #9267
- Fixes #9270
- Fixes #9271

src/scripts/app.ts

@@ -80,7 +80,7 @@ import type { ExtensionManager } from '@/types/extensionTypes'
 import type { NodeExecutionId } from '@/types/nodeIdentification'
 import { graphToPrompt } from '@/utils/executionUtil'
 import { getCnrIdFromProperties } from '@/workbench/extensions/manager/utils/missingNodeErrorUtil'
-import { rescanAndSurfaceMissingNodes } from '@/composables/useMissingNodeScan'
+import { rescanAndSurfaceMissingNodes } from '@/platform/nodeReplacement/missingNodeScan'
 import { anyItemOverlapsRect } from '@/utils/mathUtil'
 import {
   collectAllNodes,