Add friends, markers, HUD overlays, tab complete

- FriendsManager persists a per-user friend list at config/clientirc-friends.json.
- MarkerManager holds one ephemeral marker per owner (5 min expiry).
- IRC protocol extended with marker_set / marker_remove; server relays them.
- IrcService DisplayLine replaced with sealed IrcEvent (Chat / System / MarkerSet / MarkerRemove); chat formatting moved into the client.
- ClientIrcMod handles .friends add/remove/list, .marker remove, .help; chat lines from friends are prefixed with a green dot; marker events from non-friends are ignored.
- OverlayHud draws a top-center compass strip and a top-left watermark (nick / FPS / ping) via HudLayerRegistrationCallback.
- WorldOverlayRenderer draws green crosses above friends and magenta beams + base cubes at active markers via WorldRenderEvents.AFTER_ENTITIES.
- MiddleClickHandler binds MMB via KeyMapping, raycasts a block or 20-block look ray, stores locally and sends marker_set on a daemon executor.
- ChatScreenMixin completes . prefix commands on Tab; first mixin in the project, plumbed through clientirc.client.mixins.json and fabric.mod.json.

src/main/java/ru/nevetime/clientirc/IrcMessage.java

@@ -6,27 +6,55 @@ public final class IrcMessage {
     public String player;
     public String message;
     public String token;
+    public String dimensionId;
+    public Double x;
+    public Double y;
+    public Double z;
     public long timestamp;
 
     public static IrcMessage hello(String clientName, String playerName, String token) {
-        IrcMessage message = new IrcMessage();
-        message.type = "hello";
-        message.client = clientName;
-        message.player = playerName;
-        message.token = token;
-        message.timestamp = System.currentTimeMillis();
-        return message;
+        IrcMessage m = new IrcMessage();
+        m.type = "hello";
+        m.client = clientName;
+        m.player = playerName;
+        m.token = token;
+        m.timestamp = System.currentTimeMillis();
+        return m;
     }
 
     public static IrcMessage chat(String clientName, String playerName, String text, String token) {
-        IrcMessage message = new IrcMessage();
-        message.type = "chat";
-        message.client = clientName;
-        message.player = playerName;
-        message.message = text;
-        message.token = token;
-        message.timestamp = System.currentTimeMillis();
-        return message;
+        IrcMessage m = new IrcMessage();
+        m.type = "chat";
+        m.client = clientName;
+        m.player = playerName;
+        m.message = text;
+        m.token = token;
+        m.timestamp = System.currentTimeMillis();
+        return m;
+    }
+
+    public static IrcMessage markerSet(String clientName, String playerName, String token,
+                                       String dimensionId, double x, double y, double z) {
+        IrcMessage m = new IrcMessage();
+        m.type = "marker_set";
+        m.client = clientName;
+        m.player = playerName;
+        m.token = token;
+        m.dimensionId = dimensionId;
+        m.x = x;
+        m.y = y;
+        m.z = z;
+        m.timestamp = System.currentTimeMillis();
+        return m;
+    }
+
+    public static IrcMessage markerRemove(String clientName, String playerName, String token) {
+        IrcMessage m = new IrcMessage();
+        m.type = "marker_remove";
+        m.client = clientName;
+        m.player = playerName;
+        m.token = token;
+        m.timestamp = System.currentTimeMillis();
+        return m;
     }
 }
-