THE ESPLANADE     The Esplanade runs the entire length of Battery Park City, along the Hudson River from Stuyvesant High School on the north end all the way south to Historic Battery Park.   With its views of the Hudson River and New York Harbor, the Statue of Liberty, Ellis Island, and the New Jersey shoreline, the Esplanade is a pedestrian paradise. Parks and gardens line the entire route, along with numerous sculptures and public art installations.