The multi-provider panel meters hardcoded a 9x9 icon and a 3px track
inside a ~22px row, so enabling "Show multiprovider detail in panel"
produced markers that are hard to read and leave half the available
height unused (worse on HiDPI).

Derive the meter geometry from the compact representation height: the
icon takes the space left after the track and spacing, the track is 20%
of the usable height, and the width comes from one shared property so
the reserved row width and the delegate cannot drift apart. The old
9px icon stays as the floor for very thin panels.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>