With an external player on Plex, starting a never-watched episode could
open a "resume playback?" prompt at the position the previous, unrelated
file was exited. The intent carried no start hint when the item had no
resume point, so players with their own bookmark store (Zidoo native
player, VLC) consulted it - and every Plex part URL ends in the same
`file.<ext>`, so those bookmarks collide across items.
Send `from_start=true` on fresh launches and `from_start=false` beside
`position` when resuming, matching the Zidoo integrations in
jellyfin-androidtv-zidoo and PlexToZidoo. MX, Just Player and mpv ignore
the extra.
close#2223
edde746
3fc229cd6c