Ronald Reagan wanted it built, but never got to live there. Edmund G. Brown Jr. turned up his nose at it, and moved into an apartment instead. Now, California's never-been-lived-in gubernatorial mansion - built for $1.4 million as a replacement for the old mansion - may be up for sale. A Democratic-sponsored measure, authorizing the state Department of General Services to sell the mansion and put the money in a fund to find a new gubernatorial residence, was signed by Governor Brown last month. Some Republican legislators frown on the proposed sale, however, and may push to scuttle it when the legislature reconvenes in August.