feat(test-recorder): add recovery hints in gh.ts error paths after failed push or PR creation

## Summary

When `git push` fails after a commit, or `gh pr create` fails after a successful push, the user is left on an orphaned branch (`test/`) with no guidance on how to recover.

## Proposed Solution

Add recovery hint messages in the error paths of `createPr()` in `tools/test-recorder/src/pr/gh.ts`. For example, when push or PR creation fails, display instructions such as:

```
git checkout -
git branch -D
```

This would give QA testers and non-developers a clear path to clean up their local repo and retry or switch to the manual PR flow.

## Context

- Raised during review of PR #10694: https://github.com/Comfy-Org/ComfyUI_frontend/pull/10694
- Original review comment: https://github.com/Comfy-Org/ComfyUI_frontend/pull/10694#discussion_r3007032672
- Intentionally left out of PR #10694 to keep scope tight.

## Affected File

`tools/test-recorder/src/pr/gh.ts` — `createPr()` function, specifically the `push` and `gh pr create` error paths.

/cc @christian-byrne

┆Issue is synchronized with this [Notion page](https://www.notion.so/Issue-10729-feat-test-recorder-add-recovery-hints-in-gh-ts-error-paths-after-failed-push-or-PR--3336d73d3650810b9c15ebc4b72ebf05) by [Unito](https://www.unito.io)