path_helper runs after ~/.zshenv in login shells and puts Homebrew ahead of
fnm, pyenv, and ~/.local/bin. Re-source ~/.zshenv from ~/.zprofile and make
prepends idempotent so login and zsh -c resolve the same binaries.
fnm lived in interactive-only ~/.config/zshrc, so ssh/agents/zsh -c
missed fnm-managed node. Source ~/.config/zsh/*.zsh from .zshenv and
install the fragment as zsh/fnm instead.