The publish scripts shelled bare `wrangler` (ENOENT without a global install)
and the existence probes (registry.json / per-tool meta.json) printed wrangler's
'key does not exist' on a fresh bucket. Default to `npx wrangler@4` and capture
stderr on probes.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>