DAMASCUS, Syria — Some five million Syrians are now refugees in their own country, many living hand-to-mouth in vacant buildings, schools, mosques, parks and the cramped homes of relatives. Others are trapped in neighborhoods isolated by military blockades, beyond the reach of aid groups. Already desperately short of food and medicine as winter closes in, they could begin to succumb in greater numbers to hunger and exposure, aid workers say. The long civil war has forced two million Syrians outside the country ‘s borders, but more than twice that number face mounting privations at home, and the toll keeps rising. The deepening humanitarian crisis threatens to set the country’s development back decades and dwarfs any aid effort that could conceivably be carried out while the conflict continues, aid workers and analysts say. The cost of replacing damaged homes and infrastructure alone is estimated at more than $30 billion, and […]