Prepare the source (download, clone, install, etc).For sources that need preparation (e.g., git clone, download),
this method performs that preparation. For sources that don’t
need preparation (e.g., local files), this is a no-op.
Load and return the FastMCP server instance.Must be called after prepare() if the source requires preparation.
All information needed to load the server should be available
as attributes on the source instance.
