San Francisco — Gap Inc.’s board of directors has named Sonia Syngal, an accomplished retail leader and CEO of the portfolio’s Old Navy business since 2016, as the company’s next chief executive officer, effective March 23. She will also join the Gap Inc. board. Her top priority will be strengthening the performance of the portfolio. “To lead the company into its next chapter, we sought a dynamic leader who could bring a deep respect for our customers and make the decisions necessary to deliver value from our portfolio of brands …