Make Conversation a pointer refernece on Message

Instead of a value, which lead some odd handling of conversation
references.

Also fixed some formatting and removed an unnecessary (and probably
broken) setting of ConversationID in a call to
`cmdutil.HandleConversationReply`

pkg/tui/views/conversations/conversations.go

@@ -155,7 +155,7 @@ func (m *Model) loadConversations() tea.Cmd {
 		loaded := make([]loadedConversation, len(messages))
 		for i, m := range messages {
 			loaded[i].lastReply = m
-			loaded[i].conv = m.Conversation
+			loaded[i].conv = *m.Conversation
 		}
 
 		return msgConversationsLoaded(loaded)