LaunchBox produced file:// URIs relative to /romm/launchbox, but the
resources handler resolved them under /romm/library via fs_rom_handler,
so local images/manuals/screenshots were never found. Switch LaunchBox
to a distinct launchbox-file:// scheme and add FSLaunchboxHandler +
_resolve_local_file_uri to route each scheme to the correct root.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>