relative object sizes, plus a configurable reserved area at the top

[Habbie]

the reserved area at the top should (once we stop painting it white)
allow us to run "inside" Toon's qt-gui

this replaces the (already closed) #143 and already does better.
Next steps:

• instead of manually calculating our size minus the reservation, plus our y coordinate, use a parent lvgl object that holds $reserved rows and passes the rest to our row_and_logs
• deal with transparency or whatever so we never ever draw a pixel to the reserved area

Next steps for likely a later PR:

• for toon, we don't need 55 lines, we just need the rectangle for the back button on the top left. Likely we can put some fun status bar on the right 80% of those 55 lines