Track Bun.WebView Chrome launch failure on Windows #1

Upstream

Tracks oven-sh/bun#29102 and the equivalent claude-down report: kjanat/claude-down#10.

Problem

With Bun 1.3.14 on Windows x64, forcing the Bun runtime makes the Downdetector source unavailable:

$ bunx --bun github-up downdetector
Downdetector
  Unavailable: Failed to spawn Chrome (set BUN_CHROME_PATH, backend.path, or install Chrome/Chromium)

Chrome is installed and the failure still occurs when its exact executable is passed with --chrome. Running the same package without --bun follows the Node shebang and succeeds.

The current implementation returns the Bun.WebView result whenever hasBunWebView() is true. A WebView launch failure therefore bypasses the existing Chrome/CDP path, even though that path works under Node and is intended to work under Bun too.

Workaround

bunx github-up
# or
npx -y github-up

Tracking

• Re-test against a Bun release containing the upstream fix.
• Fall back to the existing Chrome/CDP implementation on Windows or when WebView initialization/navigation fails.
• Add regression coverage for a present-but-unusable Bun.WebView.
• Verify both automatic Chrome discovery and an explicit --chrome path.
• Remove any platform-specific workaround only after the upstream fix is verified on Windows.