Style tweak: make all but selected list icons rounded

In our case, "list icons" usually means "avatars" so think
"rounded avatars, except the currently selected one which remains
square". This makes things look a bit more polished, but still
allow you to properly see the full avatar when you actually need
to.

src/components/ListItem.svelte

@@ -88,4 +88,13 @@
 .list-item-indicator__subtext::first-letter {
   text-transform: none;
 }
+
+/* Make all but the selected icon rounded */
+.list-item-icon__icon {
+  border-radius: 0.6rem;
+}
+
+.list-item-icon:focus .list-item-icon__icon {
+  border-radius: 0;
+}
 </style>