ATHENS, Greece—Firefighters and residents battled a massive forest fire on Greece’s second largest island for a seventh day Monday, fighting to save what they can from flames that have decimated vast tracts of pristine forest, destroyed homes and businesses, and sent thousands fleeing. The smoke and ash from the fire on Evia, a rugged island of forests and coves almost touching the Greek mainland, blocked out the sun, turning the sky orange as the blaze rampaged across the northern part of the island. Evia’s fire, which began Aug. 3, is the most severe of dozens that have broken out across Greece in the past week, after the country was baked by its worst heat wave in three decades which sent temperatures soaring to 45 degrees Celsius (113 Fahrenheit) for days. The heat, coming amid what has already been a particularly hot summer, has turned Greece’s forests, including large areas of …