souvlaki-based players never emit MPRIS Seeked, trackid is always "/"

Rust apps using souvlaki 0.8.x with the zbus backend (e.g. some Spotify TUIs) expose MPRIS but never send the Seeked signal, and mpris:trackid is hard-coded to "/" for every track. Shells that only extrapolate position from the last sample (and refresh only on Seeked/track change) drift after any seek, including seeks from Spotify Connect devices. Confirm with dbus-monitor on the player's bus name while running playerctl position 30: no Seeked appears, only PropertiesChanged with PlaybackStatus (re-emitted ~1/s). Workaround in the client: poll Player.Position every ~2s while Playing and resync only when it drifts >1.5s from the projected position. Also check that pausing freezes at the projected position, not the last raw sample.