feat: (re)add tracking for where messages have been seen (#26)

Reviewed-on: #26
Co-authored-by: Ren Amamiya <reya@lume.nu>
Co-committed-by: Ren Amamiya <reya@lume.nu>

crates/chat_ui/src/actions.rs

@@ -13,4 +13,5 @@ pub enum Command {
     Copy(PublicKey),
     Relays(PublicKey),
     Njump(PublicKey),
+    Trace(EventId),
 }