(Reuters) -The rouble firmed past 90 against the dollar in Moscow trade on Monday, a near one-month high, while Russian stocks extended their slide lower on the third session of trading after an almost month-long suspension. The Russian market is gradually reopening after a suspension caused by sweeping Western sanctions that followed the beginning of what Russia calls “a special operation” in Ukraine on Feb. 24. Russian stocks and bonds resumed trading in full on Monday, albeit for a curtailed timeframe and with various restrictions, including a ban on short-selling, still in place. Non-resid…