Link Cupcake from snowflake.torproject.org
https://snowflake.torproject.org/#extension links to the snowflake.git extensions, but not Cupcake. We should link to Cupcake as well. We can say that all the options are equivalent in functionality; they are alternative user interfaces; Cupcake is only for Chrome; and Cupcake can run as a background app (legacy/trac#31288 (moved)).
I believe this is the correct link to Cupcake on the Chrome web store: https://chrome.google.com/webstore/detail/cupcake/dajjbehmbnbppjkcnpdkaniapgdppdnc