[Feature]: link icon

[Tealk]

Is your proposal related to a problem?

It is not apparent whether a post contains a link or not.

Describe the solution you'd like

If a post has a link, change the icon of the topic to Link.

Describe alternatives you've considered

No response

Additional context

.pm_read, .topic_read {
  background-image: url("./images/forum_link.gif");