Preserve oxlint GitHub reporter output in vp check on GitHub Actions #925

Context

PR #914 fixed vp check failing on GitHub Actions by forcing --format=default for oxlint. The root cause was that when GITHUB_ACTIONS=true, oxlint auto-switches to the GitHub reporter, which omits the human-readable summary output that vp check parses to determine pass/fail status.

While the fix resolves the immediate breakage, it loses the advantage of oxlint's customized GitHub Actions reporter output (e.g., inline annotations on PR diffs).

Problem

Currently vp check parses oxlint's human-readable summary output to produce unified pass/fail lines. This is incompatible with oxlint's GitHub reporter format, forcing us to disable it.

Desired Behavior

When running on GitHub Actions, vp check should:

1. Still produce correct pass/fail output (not break as before)
2. Preserve oxlint's GitHub Actions reporter benefits (inline annotations, structured error reporting)

Possible Approaches

• Parse the GitHub reporter output format in addition to the default format
• Run oxlint with the GitHub reporter and extract results from exit code / structured output instead of parsing stdout
• Use oxlint's --format=github explicitly and emit our own summary alongside it

References

• Fix PR: fix: failed to check inside github action #914
• Original issue: error: Linting could not start setup-vp#7