PHILADELPHIA — Zarinah Lomax is an uncommon documentarian of our times. She has designed dresses from yellow crime-scene tape and styled jackets with hand-painted demands like “Don’t Shoot” in purple, black, and gold script. Every few months, she hauls dozens of portraits of Philadelphians — vibrant, bold, bigger-than-life faces — to pop-up galleries to raise an alarm about gun violence in her hometown and America. In a storage unit, Lomax has a thousand canvasses, she estimates, mostly of young people who died from gunfire, and others of the mothers, sisters, friends, and mourners left to ask…