John, first, my most sincere congratulations. You are actually living my dream. I am genuinely happy for you, if not a little jealous.
I don't know squat about ventilation, sorry. As for cigarettes, I don't care for the smell of them myself, but I'll echo what others have said and say allow them. The way I see it, if you sell them, you have to let your customers smoke them. If cigars are your clear focus, hopefully cigarette smokers will be few.
It's a tricky thing though and the line is yours to draw. My wife is a cigarette smoker. It's hard for me to imagine that she'd have to leave a lounge to have a cigarette outside while I'm puffing away on my cigar inside. But I guess that's the way it is in some places.
As a customer in my fantasy dream shop, there'd be no cigarettes, vape pens, e-cigs, hookahs, or artificially flavored cigars. But you're opening a shop in the real world. You're a cigar man, but you're a business man. I suppose much depends on your clientele. It would be great if only cigar smokers--and lots of 'em--walked through your door. But, who'll be walking in? Jazz people. I'd bet that there are a lot of cigarette smokers among the jazz crowd.
Let us know how you decide to handle it.