WebSocket client + CLI harness + pytest suite that exercises each axis of
a CKBunker + Coldcard Mk4 policy and asserts the expected outcomes, including
the critical negative test that a large PSBT without TOTP is rejected with
a specific 'rule #1: need user(s) confirmation' reason.
Configuration via .env / YAML / CLI flags, two pre-crafted test PSBTs as
fixtures (generation guide in fixtures/README.md), dashboard counter
scraper as sanity check, design rationale in docs/.
