Not peace, exactly, but a truce of sorts seems to have been negotiated. Both cats have the run of the house now, and that seems to be working better than confining either of them did, even this morning when Tori was still very much on edge. She still hisses and snarls at Lexi whenever she decides he's invading her space, but the rest of the time they are calm, and he's not striking back at all. After a couple of thwacks when he wouldn't back off, he's learned to keep his distance when she's growling, to the point that I was comfortable leaving them alone for a few hours to go to chorus.
So things are better. I hope they continue to improve -- we could live with the current situation, I think, but everyone would be happier if the cats were friends again. Hopefully all it needs is time.