Any of the Pentax AF SLRs with built-in flash can switch to MF. I do this particularly when I'm shooting infrared, or if I'm in the mood for wide-angle and small aperture. For example, I can set a 28mm lens to f/8 and 10 feet. Everything from 5 feet to infinity is in focus. It's gonna be bigger than your small Olympus cameras, but they're out there.
If you want a small SLR, the Pentax M-series SLRs will be smaller than the Pentax AF cameras, but they're not gonna have a built-in flash, which was one of your requirements. Grab an ME Super and a pancake lens, and it's practically pocketable. But no built-in flash.
Geez, now I've just about talked myself into getting another Pentax M-series body. The MX is all mechanical and needs no batteries except for the light meter.