v1.6.1 — world-class first-run

First run leads with uvx hotato start --demo everywhere, so the first command works on a machine with an externally managed Python (PEP 668). pip stays shown for CI and containers, pipx or a virtualenv for a project install.

The demo and contract verify output reads as a designed surface: a metric with no finite value shows n/a, times carry their s unit, and a bundle whose canonical digest matches reads as integrity: intact (the stored authenticity field and schema are unchanged). The start --demo exit-code note is stated plainly (setup exits 0; the CI gate returns exit 1), and the epilogue is a verb-first aligned block.

Full suite 3522 passed; verified end to end from a fresh install.