Function should_apply_iterm2_profile 

pub fn should_apply_iterm2_profile(
    iterm_session: bool,
    tmux_session: bool,
    profile_installed: bool,
) -> bool

Pure gate for the one-shot iTerm2 profile switch.

Switch only for a real iTerm2 session outside tmux (proprietary sequences do not pass through multiplexers) with the shipped profile installed, so removing the profile file disables the switch.