The prospective owner of a small strip of oceanfront property in Deal has agreed to build a staircase to allow public access to the beach, ending a three-year legal battle in this tiny Monmouth County borough. Isaac Chera wants to buy the strip of borough-owned land at the end of Neptune Avenue for $1 million. But he’s been opposed by the American Littoral Society, which filed a lawsuit in 2019 to block the sale. This week, the American Littoral Society announced it has reached a settlement with Chera and the borough that will allow the sale to go through. The borough will design a staircase o…