When it comes to Friday night plans, there’s a happy medium between sitting home alone with a beer and a Netflix envelope and staying out till 3 a.m. in Adams Morgan. The Smithsonian provides middle ground for those of us who prefer to end our weeks by going out and enjoying a relaxing dose of culture. Friday evenings you can find live jazz from 6 to 10 p.m. at the Smithsonian Jazz Cafe. Think harmonic…