By Ashley Cowburn Scotland’s First Minister Humza Yousaf has dramatically quit sending the SNP into meltdown. After just a year in charge, he resigned today ahead of votes later this week that could have brought down his leadership and his Government at Holyrood. Delivering his resignation statement, Mr Yousaf said he “clearly underestimated the level of hurt and upset caused” after he terminated a power-sharing agreement with the Greens. Mr Yousaf is understood to want veteran MSP John Swinney, who served as Nicola Sturgeon’s deputy, to take over as SNP leader. Other candidates may include Ka…