This is probably more manual steps than /resolve, but it is "from the website." The sound id also appears in the embed code when you go to the sound and click "Share".
For example, if you go to a sound page, e.g.:
https://soundcloud.com/lowcountrykingdom/another-ordinary-day
Then click "Share", which brings up a pop up. Click "Embed" to switch to the embed tab, and copy the Embed code, which will look something like:
<iframe width="100%" height="166" scrolling="no" frameborder="no" src="https://w.soundcloud.com/player/?url=https%3A//api.soundcloud.com/tracks/47580057&color=ff6600&auto_play=false&show_artwork=true"></iframe>
Note the ID in the value of the url query parameter:
url=https%3A//api.soundcloud.com/tracks/47580057