PNGdec (bitbank2, 1.1.6) decodes a tile a row at a time straight into
RGB565, without lodepng's 256 KB RGBA buffer; the trail overlay goes through
it too, blended by hand for palette-with-alpha and RGBA. It lives in its own
file (ui-lvgl/TilePng.cpp) because its zlib headers put DONE/EXTRA in the
global namespace. lodepng stays the fallback and the sim's decoder.
Same 20 tiles: decode 78 -> 50 ms, trails 42 -> 17.5 ms, a whole tile
170 -> 105 ms; the map with trails is pixel-identical.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
