Fetch the game's cover art (libretro / ScreenScraper / IGDB / Wikipedia,
reusing the local cover cache) and bake it into the EBOOT's ICON0 (144x80
XMB icon) and PIC1 (480x272 launch background) instead of the default PS1
icon. Best-effort: falls back to the base icon/empty background when no art
is found. convert()/convert_to_folder() gain optional icon0/pic1 params.