omz_termsupport_preexec: only use first part of jobspec with title
Enhance/clenaup zsh theme

  - path segment coloring
  - use %~
  - drop `hostname -f` (slow)
zshenv: improve $path adjustment: only add/append if missing
zshenv: prefer /u/l/b/vim as EDITOR, cond. source ~/.zshenv.local