feat: add underline to links within text

[coseeian]

To address: #1505 .

Summary

• styles/markdown.scss: add persistent text-decoration: underline to prose links inside .rendered-markdown, scoped as a:not(.button-link) so styled button links are excluded.

[limzykenneth]

They are mostly there but there are some false negatives:

These probably should be underlined as well.

These in community sketches too perhaps

Should these be underlined too?

I wonder if there is somewhere in the CSS rules that applies the p5 magenta highlight we can add the underline rule at the same place then we'll catch more or less the places we want to have underlines? Unless that introduce too many false positives.

[coseeian]

Let me take a look.