Add UI improvements and switching state for branch menu and implement remote-branch-aware checkout logic.
Frontend: add CSS for disabled branch items, compact branch name layout, subtitles and messages; show switching indicator and disable branch actions while switching; display local/remote names and remote subtitles; surface branch switch errors and in-progress messages. Add state.branches.switchingTo and update event handlers to set/clear it.
Backend (tauri): extend LocalRepoBranch with is_remote, remote_name, local_name; add git_ref_exists helper; enhance checkout_branch to detect local vs remote refs and automatically checkout or create tracking branches for remotes; parse refs to include remote branches (skip ones with existing local counterparts) and sort branches with current/local/remote order. Minor formatting tweaks.
andrew
4e6d665c59