Leica has a new camera for pros who shoot both video and stills. The $5,295 Leica SL3-S, which launches today, is a full-frame mirrorless hybrid camera optimized for fast-action stills and 6K video. Like the SL3 it’s based on, the SL3-S has a compact body and 3.2-inch tilting touchscreen display. But where the SL3 with its 60mp sensor is mainly for still photography, the SL3-S is optimized for speed: its 24mp sensor can shoot video at 6K with 12-bit raw footage, and it can capture stills…