With a slice of pizza in one hand and a brush in the other, Julia LaChica worked with about a dozen others in paint-splattered aprons Thursday on a banner that eventually would read: “Japanese Americans say: Stop repeating history. No more camps. ICE out of CA.” The art build, at the Richmond studio of art activist David Solnit, moved quickly from tracing to cloth cutting, to painting, and screen printing, ending in three large yellow banners and hundreds of small…