I did not think to mention this earlier, because it is so well integrated into our regular routine with Raven, but she needs daily medication for a chronic medical condition. It's not a problem so long as she gets her regular medication but without it, over time the problem will show up again and will get serious. And now it's been two days since she last had her medication, so that sucks, and lends to the urgency of finding her quickly.
The medical problem is expensive and time-consuming to deal with (the medication costs a bit of money plus regular vet care plus pills down her throat at each meal) but we love her so we deal with it. I'm going to edit the initial post so as to make sure this important information is covered there.
Otherwise, no new word. We've checked the four area animal shelters in person with no result. My brother, who is a smart waste water engineer, suggested that lost dogs might want to go into local creeks, and that we contact the Santa Clara Valley Water Authority so as to make their field crews aware of Raven's loss. So I did that this afternoon.