Disposable rig that runs the onboarding-tester agent docs-only against the
buyer-pays journey: a sandbox daemon wired to a Dockerized BTCPay regtest stack,
a scoped key with payment_providers:write, and a regtest buyer-pay helper.
Includes the de-risk probe + findings and an end-to-end gate check
(validate-gate.sh, 10/10). The doc-onboarding loop converged completed-clean;
see stage2/STAGE2-RESULT.md. Scratch (.live-env, probe-out/) is gitignored.
Grant