busctl cannot convert some BlueZ advertisement data (Apple
ManufacturerData, a{qv}) to JSON, so GetManagedObjects failed as soon as
an iPad was paired and the web showed no devices at all. Read only the
needed Device1/Adapter1 properties per object instead. Also publish the
web mixer as an _http._tcp Avahi service.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>