Allow copying individual links from chat context menus

## Feature request

Links in chat cannot currently be copied individually from the context menu. Right-clicking a link and choosing copy copies the entire chat response instead of the link target.

Add a context-menu action that copies the selected link address without copying the rest of the chat content.

### Steps to reproduce

1. Open a chat response containing a link.
2. Right-click the link.
3. Choose the available copy action.

**Actual:** The whole chat response is copied.

**Expected:** The selected link address can be copied on its own.