## Summary
Add deterministic mock data fixtures for browser tests so they can use
`page.route()` to intercept API calls without depending on a live
backend.
## Changes
- **`browser_tests/fixtures/data/nodeDefinitions.ts`** — Mock
`ComfyNodeDef` objects for KSampler, CheckpointLoaderSimple, and
CLIPTextEncode
- **`browser_tests/fixtures/data/systemStats.ts`** — Mock `SystemStats`
with realistic RTX 4090 GPU info
- **`browser_tests/fixtures/data/README.md`** — Usage guide for
`page.route()` interception
All fixtures are typed against the Zod schemas in `src/schemas/` and
pass `pnpm typecheck:browser`.
┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-10662-test-add-mock-data-fixtures-for-backend-API-responses-3316d73d3650813ea5c8c1faa215db63)
by [Unito](https://www.unito.io)
---------
Co-authored-by: dante01yoon <bunggl@naver.com>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Co-authored-by: GitHub Action <action@github.com>
