The cargo-new mirror completed: a scaffold landing inside a tracked
tree no longer nests a .git (the gitlink/submodule hazard that bit the
fieldtest corpus); outside a work tree the best-effort init is
unchanged. Oracle: git rev-parse --is-inside-work-tree in the target
dir; any failure reads as not-in-a-work-tree so the init stays
best-effort.
RED-first (tdd-author handoff): the inside-a-work-tree pin observed
failing on the nested .git; the outside guard pinned against
over-removal.
Gates: workspace 1003/0, clippy -D warnings clean.
closes#204
Brummel
4da47cb919