test(pm): pin the three-dot derivation, its refusals and the card's reproduction

A new self-test battery (43 cases): the Link page walk, a rename reaching the
predicate as both of its paths, a walk the PR's own count contradicts, the
channel chosen once and never spliced mid-walk, every --branch leg on an
injected git, and the card's own reproduction run end to end on a real repo —
a branch behind a main that has since touched a governed path answers GOVERNED
two-dot and NOT governed three-dot, and the verdict is byte-identical through
--branch and through --test on the same list.

Claude-Session: https://claude.ai/code/session_01YKEjmbYNvYWJvWGSWx26zK
Co-authored-by: Claude <noreply@anthropic.com>

Author: claude