- Replace git pull with fetch + merge to avoid conflicts with global
git config (e.g. pull.ff=only) and background fetch --all
- Disable commit/commit+push buttons when message is empty
- Always show Push/Pull menu items even without remotes configured
- Default remote name to 'origin' when adding a new remote
Add new_xplatform_command() helper in yaak-common that creates a
tokio::process::Command with CREATE_NO_WINDOW flag set on Windows.
Also converts git commands to async for consistency.
