By Nidal al-Mughrabi and Dan Williams GAZA/JERUSALEM (Reuters) – Israel and Palestinian militants agreed to a Cairo-mediated truce to take effect late on Sunday, sources said, raising hopes of an end to the most serious flare-up on the Gaza frontier in more than a year. Israeli forces pounded Palestinian targets through the weekend, triggering longer-range rocket attacks against its cities. Islamic Jihad, the faction that Israel has been fighting in Gaza since Friday, and a Palestinian official familiar with the ceasefire efforts said the truce would come into effect at 23:30 (20:30 GMT). Isra…