Use URL fragment for share button

Right now it uses the URL query string, which can be sent to a server. It's not sent to our servers, but it is sent through DNS. It should use the URL fragment, which is only sent to the browser.

Start by locating the share button and the code that builds its URL. Confirm how the current query string is assembled, then verify the shared value is placed in the URL fragment and is not sent to the server. Test the share flow in a browser, including opening the generated link.

Written by the indexing model from the issue text.