Seeing that you can start and drive the car I don't think that it can have anything to do with the steering lock, but I can be wrong.
I'm surprised that the manual cars do not have the ignition release.
Looking at my manual from my 99 Forester it does say for manual transmission vehicles ; "The key can be turned from 'ACC' to 'LOCK' only when the key is pushed in while turning it."
Next suggestion would be try spraying a little lube around the key hole, maybe some of the lube will drip in and free some of the parts up, if that could allow the key to be pushed in a little bit more.
I'm just throwing this out there for now but try disconnecting the battery, drain any reserve power, pump brakes, turn lights on (interior and exterior) etc. wait about 15 minutes then reconnect the battery. I doubt that it will affect anything but you never know if power to the ignition might be causing it to stick(?)
I'd be trying anything at this point.
Do let us know if you find a solution that works, it'll help us help others.