part placement, routing, DRC, silkscreen, replace mounting vias with holes and polygon cutouts; fusion sync, update exports

add a separate pull-up to GPIO8, add a solder jumper for USB power bypass, add hardware pull-downs to the main switching transistors, enlarge D1 & D2 solder pads, move the USB connector 0.25mm to the right

fix the barrel jack footprint, replace jumper library, adjust silkscreen text; Fusion sync, image exports