sysutils/atuin: import atuin-18.19.0

Atuin replaces your existing shell history with a SQLite database and
records extra context (exit code, cwd, duration, host, session) for each
command.  It offers a full-screen fuzzy history search (bound to ctrl-r
and the up arrow) and optional end-to-end encrypted sync between machines
through a self-hosted or hosted Atuin server.

This package provides both the atuin client and the atuin-server daemon,
with an rc.d script (atuin-serverd) and a dedicated _atuin user for the
server.
