Welcome back to IPO season. No, we won’t call it hot liquidity summer, but after an August lull, the public-offering cycle is back upon us. Last week we saw filings from Warby Parker, Toast and Freshworks. We’ve dug into Warby already. This week, we’re tackling the details of the latter two debuts, starting with Toast. The Exchange explores startups, markets and money. Read it every morning on Extra Crunch or get The Exchange newsletter every Saturday. Why do we care about Toast? It’s a technology startup. It’s a unicorn. And…