Corrected mouse position during focus if scaleX.ori is 1

[leeoniya]

thank you!

i fixed this by moving up the mouseYPos var from inside the bias block that's a bit lower.

also added some focus opts to the orientation demo: https://leeoniya.github.io/uPlot/demos/scales-dir-ori.html

[alex-tel]

Could you please add this (in the red circle?) without it, vertical series is not focused (tested when each series has own scale)

[leeoniya]

i added this change in the linked commit above (https://github.com/leeoniya/uPlot/commit/baec062a89b9c13746e8cc602d420d6974da8fd9)