sims only invokes emacsclient (in modules/notmuch.py) and never the
full emacs binary. Bundling emacs onto the wrapper PATH was forcing
consumers to pull in an extra ~310M emacs closure (often a different
version from the user's actual editor). Rely on the consumer's
emacsclient via PATH, configurable via services.sims.settings.notmuch.emacsclient_command.
