- ChatView: change useEffect dependency from [activeThread] (new object
  ref every dispatch) to [activeThread?.id, activeThread?.worktreePath]
  so envMode is no longer silently reset to "local" on unrelated store
  dispatches, making the worktree code path reachable.

- git.ts: replace shell command strings (runTerminalCommand + single-quote
  escaping) with a runGit helper that spawns git directly via argv array.
  Eliminates Windows quoting issues and the command injection surface.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>