fix(pyenv): preserve shims in login shells

macOS path_helper runs after .zshenv and can move system Python ahead of pyenv. Add an idempotent login hook and preserve it across later easyzsh migrations.

zsh/pyenv.zsh

@@ -1,7 +1,8 @@
 # pyenv (Python Version Manager), always-on via ~/.zshenv
 export PYENV_ROOT="${PYENV_ROOT:-$HOME/.pyenv}"
-[[ -d "$PYENV_ROOT/bin" ]] && export PATH="$PYENV_ROOT/bin:$PATH"
-[[ -d "$PYENV_ROOT/shims" ]] && export PATH="$PYENV_ROOT/shims:$PATH"
+[[ -d "$PYENV_ROOT/bin" ]] && path=("$PYENV_ROOT/bin" ${path:#$PYENV_ROOT/bin})
+[[ -d "$PYENV_ROOT/shims" ]] && path=("$PYENV_ROOT/shims" ${path:#$PYENV_ROOT/shims})
+export PATH
 if [[ -o interactive ]] && command -v pyenv &> /dev/null; then
   eval "$(pyenv init - zsh)"
 fi