By Sruthi Shankar and Shreyashi Sanyal (Reuters) – European stocks rose on Monday, clinging to hopes of diplomatic efforts by Ukraine and Russia to end weeks-long conflict, while shares in Volkswagen surged after the German carmaker doubled its operating profit. The pan-European STOXX 600 index ended 1.2% higher, extending gains from Friday when Russian President Vladimir Putin signalled a positive shift in talks with Ukraine. Russia and Ukraine gave their most upbeat assessments following weekend negotiations, even as Russia attacked a base near the Polish border and fighting raged elsewhere….