Hacks was a show about legacy. That wasn’t its only subject; comedy and power and misogyny and creativity and intergenerational conflict and work ethic and, especially in its last few seasons, the debased state of the entertainment industry were all richly explored through lines. But when we met the septuagenarian comedian at its center, Jean Smart’s Deborah Vance, the most compelling problem facing her was that, for all the millions of dollars she’d earned and all the thousands of sets she’d performed, she had yet to receive the recognition she deserved as a pioneer of her art form. Decades into a Vegas residency where she recycled moldy jokes and a staple of QVC, this workhorse was seen by just about everyone besides her obsessive fans, the Little Debbies, as a hack. It seemed inevitable that this was how she would be remembered.  Then she met Ava Daniels, a newly canceled young comedy writer played by then-unknown, now-indispensible comedian Hannah Einbinder .…