## Summary
Add Playwright e2e tests for the node replacement feature (swap nodes UI
in the errors tab).
## Changes
- **What**: 6 e2e test cases across two describe blocks covering single
and multi-type node replacement flows. Tests verify swap nodes group
visibility, in-place replacement, widget value preservation, Replace All
across multiple types, output connection preservation, and success toast
display. Includes typed mock data for `/api/node_replacements` and two
workflow fixture files with fake missing node types mapped to real core
nodes.
## Review Focus
- Mock setup pattern in `setupNodeReplacement` — enables feature flag
via `page.evaluate` and routes the API endpoint
- Workflow fixture design — uses fake node types (E2E_OldSampler,
E2E_OldUpscaler) that map to real registered types (KSampler,
ImageScaleBy)
- Assertion coverage for link preservation after replacement
┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-11242-test-add-e2e-tests-for-node-replacement-flows-3426d73d3650811e87d7f0d96fd66433)
by [Unito](https://www.unito.io)
---------
Co-authored-by: Connor Byrne <c.byrne@comfy.org>
