Shell hygiene: simpler reload, pyenv shim cleanup, ignore rules

- zshrc-dev: reload now execs a fresh zsh instead of re-sourcing
- zshenv: remove stale pyenv-rehash temp shim (>1min old) before init
- gitignore_global: ignore .claude/settings.local.json
- zshrc-natera: drop the git switch main->master wrapper

zshrc-natera

@@ -97,15 +97,6 @@ kb-publish() {
   echo "Site published."
 }
 
-# Natera repos use master as primary; rewrite "git switch main" to "git switch master"
-git() {
-  if [[ "$1" == "switch" && "${2:-}" == "main" ]]; then
-    command git switch master "${@:3}"
-  else
-    command git "$@"
-  fi
-}
-
 # Sensitive values (AWS profile, OTEL endpoint, cert paths, refresh alias) are in zshrc-natera.private
 # Copy zshrc-natera.private.example to zshrc-natera.private and fill in. That file is gitignored.
 [[ -f ~/dotfiles/zshrc-natera.private ]] && source ~/dotfiles/zshrc-natera.private