Extract GitView's resolution flow into hooks/useNestedGitDirectory (root
probe, discovery, auto-select, stale-selection recovery) so the flow no
longer depends on SessionSidebar probing the root first, and reuse it in
the pull-request view, walkthrough view, and mobile changes surface —
all three now operate on the selected nested repository instead of
dead-ending on a non-repo root. Shared pending/failed/unsupported/empty
states live in git/NestedRepoResolutionStates; desktop changes inherits
the behavior through GitView. Selection stays shared per root, so the
picker's pick carries across surfaces.
jaygupta17
cda273d69f