v2.4

Full Changelog:

What's new

Layer masks — show/hide each background and sprite plane. A new Layers tab in Debug tools lets you toggle SCR1, SCR2, and the three sprite groups (back / mid / front) independently, with solo, a live preview, and PNG export. Because text and background always live on separate planes on this hardware, hiding a plane answers "which layer carries this text?" and gives you a clean background sheet — without touching VRAM.
exemple:

Library covers no longer render as white boxes. Covers are drawn by booting each game, which needs a real bios.bin; with none, a game never reaches its title screen and every card came out a blank box — and that blank frame was then cached, so it stayed white even after a BIOS was added. Now blank captures are never cached, no game is booted without a BIOS, covers re-render automatically once a BIOS is set, and the Library says why the cards are empty.

Fixes

The BIOS is no longer described as optional — both start modes require it, and games won't run without one.
Fixed a nav-label wrapping test that failed on Linux/macOS CI due to font differences.