Dev supervision tree for local mix/iex sessions.
Boots the simulated Dev.TestRobot under BB.Supervisor plus an
ExRatatui.Distributed.Listener pre-wired to BB.TUI.App.
Having the listener up at boot means any connected BEAM node can
attach with ExRatatui.Distributed.attach/2 without further setup
on the robot side — just start iex --sname robot -S mix on this
app and attach from a second node. See the README's
"Testing distribution locally" section for the two-terminal recipe.