Route chat output through LocalPlayer.displayClientMessage

Gui.chat is private in 26.2 and Gui.getChat() is gone, so the previous
direct-field access does not compile. Player.displayClientMessage is a
public, stable API for client-side chat output, so push everything
through it. When the player is null (e.g. on the title screen before
join, where the auto-connect "Connected to ..." line lands), fall back
to the logger so the message is not silently dropped.

src/client/java/ru/nevetime/clientirc/ClientIrcMod.java

@@ -112,8 +112,10 @@ public final class ClientIrcMod implements ClientModInitializer {
             return;
         }
         client.execute(() -> {
-            if (client.gui != null && client.gui.chat != null) {
-                client.gui.chat.addMessage(text);
+            if (client.player != null) {
+                client.player.displayClientMessage(text, false);
+            } else {
+                LOGGER.info(text.getString());
             }
         });
     }