[Bug]: Claude review wont't work on forked branches

[priyansh4320]

Describe the bug

The Claude review Action fails due to missing files, as shown in PR #2097
But the files are actually present on a forked branch priyansh4320:simplify-docagent
A Claude review action runs on a non-forked/upstream branch.

      at genericNodeError (node:child_process:941:13)
      at checkExecSyncError (node:child_process:449:27)
      at execFileSync (node:child_process:268:31)
      at <anonymous> (/home/runner/work/_actions/anthropics/claude-code-action/v1/src/github/data/fetcher.ts:219:21)
      at map (1:11)
      at fetchGitHubData (/home/runner/work/_actions/anthropics/claude-code-action/v1/src/github/data/fetcher.ts:208:40)

Found 2 image(s) in pr_body 2097
Downloading https://github.com/user-attachments/assets/80f17a02-c192-48f1-925d-d2b19eef3890...
✓ Saved: /tmp/github-images/image-1760598646774-0.png
Downloading https://github.com/user-attachments/assets/978e3924-08f8-4796-bf6c-c8f4fd9695a8...
✓ Saved: /tmp/github-images/image-1760598646857-1.png
This is an open PR, checking out PR branch...
PR #2097: 11 commits, using fetch depth 20
fatal: couldn't find remote ref simplify-docagent