Derive panel size from outputs
This was attempted before in !340 (closed)
This MR doesn't include all the mathy parts, but rather attempts to untangle some mess: duplication, unneeded modules, and weird data flows.
EDIT: Some untangling was split out for another batch; this one is quite useful already as it.
It culminates in a Squeekboard that reacts to output sizing changes in a unified way, and has a hard limit on 1/2 height.
Draft because it's ignoring width.
Draft because it's based on !524 (merged)