fix(gui): remove duplicate isEditing Show block in InteractiveRebase (#332)

- Remove duplicate isEditing() Show block in CommitRow component that was
  causing double rendering of Save/Cancel buttons when editing commit messages
- Fix CRLF line endings in InteractiveRebase.tsx

Part of AGENT4 Git components audit per cortex-gui/orchestration/AGENT4.md

Co-authored-by: Droid Agent <droid@factory.ai>

Author: echobt