Exporting playground and restoring the zip file leaves image urls broken - they point to the previous site scope instead of the new one.

Let's rewrite those scope references during the .zip import process.

One easy way of doing that would be including the scope in the zipped export and running an SQLite update query to replace the scope:name substring - which is reasonably unique and unlike to be encoded as something different than ascii.

A more reliable way would be repurposing the WCR URL rewriting pipeline, but that will require more effort and we'll get there anyway as a side-product of the WordPress importer plugin work so we might as well do the UPDATE query for bow and migrate to this pipeline eventually.