Allow filtering by episode length

We tend to have a ‘short’ show and a ‘long’ show in progress at the same time so that we have something to fit in depending on the time we have available.

I have a bunch of shows marked as Planned but as far as I can tell there isn’t any way to filter that by general episode length.

I suspect that mean would be the best statistical method as most shows don’t tend to have numerous runtime outliers.