UMBERTO BACCHI SHELTERING in chilly school buildings and mountain sanatoriums, thousands of Armenians are bracing for a harsh winter after being driven from their homes by six weeks of fighting over the Nagorno-Karabakh enclave. About 90,000 ethnic Armenians fled the mountainous enclave with the little they could take during the short war with Azerbaijan that ended with a Russian-brokered peace deal earlier this month, according to the United Nations. As temperatures fall, some people want to return to the area, but widespread damage and unexploded ordnance means many could be stuck for months in temporary accommodation - either with relatives…