RevParseHeadAsync and CommitAsync's identity-error detection match
English-only substrings against git stderr. Under a non-English OS/git
locale these silently fail to match, falling through to a generic
error. Force LC_ALL=C and LANGUAGE=C on the git ProcessStartInfo so
git always emits English output regardless of ambient locale.
A fresh 'git init' repo (unborn HEAD) failed every worktree-based flow with raw
git stderr ('ambiguous argument HEAD'). EnsureHeadCommitAsync now creates an
empty initial commit via plumbing only (mktree/commit-tree/update-ref) so the
user's index and working tree are untouched; broken HEADs get a clear error.
CommitAsync retries once with a ClaudeDo identity when the machine has none,
and RevParseHeadAsync reports 'no commits yet' instead of raw git output.
Also: git stdin is now BOM-less UTF-8 (git rejects BOM-prefixed input).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
(cherry picked from commit 21af231f3e7b2cf056efe475916627f0cfeeb5c6)
mika kuns