Anyone with access to your account (this would include root) on a machine which you have forwarded your agent to can use it to authenticate as you. For your use

Anyone with access to your account (this would include root) on a machine which you have forwarded your agent to can use it to authenticate as you. For your use case, the least evil option would be to set up an SSH key that is restricted on the SVN server to only be able to do an svn export.