Make pretty oneboxes for Garmin and Strava URLs.
Garmin takes URLs like https://connect.garmin.com/modern/activity/1234 or https://connect.garmin.com/modern/activity/1234?share_unique_id=5 and changes them into an <iframe> (that you could copy from the Garmin share site and paste in yourself). Finding and pasting the iframe is more than most people can muster. With this theme component people can just paste in the URL from their browser or phone.
Strava takes urls like https://www.strava.com/activities/1234 and converts them into an embed like
<div class="strava-embed-placeholder" data-embed-type="activity" data-embed-id="1234"></div><script src="https://strava-embeds.com/embed.js"></script>
which can be copied by clicking the share icon. Discourse will not allow an arbitrary <div> or <script> elements to be inserted, so pasting that in would do nothing. With this theme component, you can just paste in the URL from your browser.
content security policy script src needs https://strava-embeds.com/embed.js in order for Strava's script to be allowed.
allowed iframes needs https://connect.garmin.com in order for the <iframe> to be allowed.
If you get a share link from the strava app, you'll get something like https://strava.app.link/A09cutdulzb, which isn't easily converted into something that I can configure out how to make pretty.
Move this to github. Right now, it's just directly loaded into the database.