The connected-peers rate and sparkline shared one grid cell, so the plot still
moved right as the rate text grew (e.g. "1.0 kB/s"). They are now two separate
grid columns — the plot column starts at the same x on every row, since grid
columns align.
The devices window also gets its own pkts/bytes toggle, bound to the same unit
setting as the main window so the two stay in step.
Builds and is clippy-clean (-D warnings) on macOS; not run in this headless
session.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>