Full compatibility with WebKit

[mattyg]

Ensure app works identically on WebKit as Chromium / Firefox

Overview

• Regexp look-behind not supported (Regex Invalid when running in launcher (thus app fails to load) #114)
• Some quasar styling elements render improperly (search input)
• Mew submit button doesn't seem to work

[harlantwood]

One possibility for some of these issues is to do a basic smoke test (even just load the feed page) in playwright, which tests in all major browsers out of the box, and can be configured to fail on js errors— like the regex issue for example.