One of my favorite annual events — one that’s beautiful both inside and out — is about to hit the city this weekend. On Sunday, more than 70 top hair salons across the Boston area will be part of the ninth annual HAIRraising Cut-a-thon fundraiser. What does that mean for you? You can get a gorgeous cut just in time for your fabulous spring makeover. And 100 percent of all haircut proceeds benefit the Heart Center at Boston Children’s Hospital.