Corners were drawn by two disagreeing algorithms: a hand-rolled per-row inset for
the gradient fill and TFT_eSPI's Bresenham arc for the border, so they missed each
other by a pixel and left a halo. The inset was also wrong, truncating the sqrt and
ignoring pixel centres, which over-cut the top row by 2px into a visible chamfer.
gui.roundRect now derives fill and border from the same signed distance, blending
edge pixels by coverage, and replaces fillRoundRect, drawRoundRect and
fillRectGradient. The geometry moved to src/gfx/round_rect.h so round_rect_test.cpp
can check the arc on the host, since only the eye ever checked the old one.
Every app re-declared the same black/white/accent triple, so a palette now lives in
/lib/theme.lua and ui.lua derives muted, contrast, gradients and radius from it.
Deriving rather than listing means a new component costs no theme keys, and a theme
cannot pick text that is unreadable on its own accent.
Components take the palette by inheritance, so the three apps name no colors at all;
ui.theme stays for drawing outside the tree. Settings cycles the installed themes and
stores only the name.
evan