CursedBrogue SDL_gpu Effects Preview

Windows preview build for the SDL_gpu visual effects pass.\n\nIncludes:\n- SDL_gpu combat hit sparks, damage popups, and death remains.\n- Footstep dust, grass movement, and water ripple effects.\n- Render ordering fixes so floor effects stay behind player, creature, and item sprites.\n- Bundled CursedBrogue game, assets, DLLs, tile picker, and TileManager.\n\nVerified with focused SDL_gpu visual regression tests, HUD popup checks, diff check, and tools/package-windows.ps1.