In 2009, where were Bitcoin source codes stored?
2008
We don't know if Satoshi Nakamoto is an individual or a group, but Satoshi Nakamoto asked for professional crypto geeks to review his project in 2008.
The original source files were therefore distributed privately through email.

2009
Unsure if Satoshi Nakamoto used any kind of source control before the source codes were available to the public. You probably have to ask the developers that were involved.
First available on Sourceforge.
Initial commits on GitHub were converted from svn on Sourceforge.