Dev-only command that emits a high-rate burst of synthetic JointState
sensor messages on [:sensor, :simulated], sweeping a joint through a
sine motion for ~2s at ~100Hz.
Its purpose is to make the dashboard's high-rate handling visible: the
joints panel animates smoothly because sensor-driven renders are
coalesced to ~30fps, while the event log shows a single debounced
JointState row per second instead of hundreds. Run it from the
Commands panel and watch the Events count stay calm while the joint
bar sweeps.
Mirrors Dev.MoveHandler's publish pattern; the burst runs in the
command's own process (so the TUI keeps rendering), returning the state
machine to its initial operational state when done.
Goal shape: %{joint: atom()}.