Fix crashes due to large content time jumps in updateDurationStats in media tracking

Add a MAX_CONTENT_TIME_STEP (3600s) gap guard to the playedSeconds fill loop
in updateDurationStats. When contentTime jumps beyond this threshold (e.g.
live stream epoch offsets or large VOD seeks), the per-second loop is skipped
and only the current second is recorded, preventing RangeError crashes from
unbounded Set growth or billions of iterations.