Implement canonical URLs

[guimachiavelli]

Due to our increasing use of utm query parameters, some of the navigation data is getting distorted by e.g. example.com and example.com?key=value being considered different pages.

We can solve this by establishing canonical URLs for all pages.

(Thanks for the heads up, @qdequele!)

Tasks

• Research how to implement canonical URLs in next.js and figure out if it's something we can do programmatically