Two MPV-side fixes for the same failure story — a wifi blip during
playback.
The demuxer gave up the moment a read failed and MPV raised
EndFile(ERROR), so a momentary outage killed the track outright. Enabling
ffmpeg's reconnect options handles the common case entirely below our
level, so most outages never reach the recovery path at all. Set
non-fatally: their availability varies with the libmpv/ffmpeg build, and
losing resilience is not a reason to refuse to play anything.
Separately, `time-pos` and `duration` are live properties of the *loaded*
file: at EOF MPV unloads it and both stop resolving. Reading them straight
through returned 0.0/unknown at exactly the moment end-of-file handling
needed to know where playback had reached, so the player appeared to
rewind to 0:00 as a track ended. `ObservedTime` records the last reading
seen while media was loaded and the accessors fall back to it.