* Add per-file line counts to the source control sidebar
Show +N/-N (green/red) next to each file in the Changes, Untracked, and
Committed-on-branch sections so the magnitude of a change is visible at a
glance. Counts are computed per staging area via `git diff --numstat`;
untracked/new files count their full contents as additions and binary
files show no count.
Consolidate numstat parsing and binary-buffer detection into shared
modules reused by the local status path, the SSH/relay path, and the
existing branch-compare code. Include added/removed in the status-entry
equality check so the sidebar doesn't re-render on unchanged polls.
* fix: harden source control line counts
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Co-authored-by: Neil <4138956+nwparker@users.noreply.github.com>
