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/client/java/ru/nevetime/clientirc/OverlayHud.java

@@ -0,0 +1,126 @@
+package ru.nevetime.clientirc;
+
+import com.mojang.authlib.GameProfile;
+import net.fabricmc.fabric.api.client.rendering.v1.HudLayerRegistrationCallback;
+import net.fabricmc.fabric.api.client.rendering.v1.IdentifiedLayer;
+import net.minecraft.client.DeltaTracker;
+import net.minecraft.client.Minecraft;
+import net.minecraft.client.gui.Font;
+import net.minecraft.client.gui.GuiGraphics;
+import net.minecraft.client.gui.LayeredDraw;
+import net.minecraft.client.multiplayer.PlayerInfo;
+import net.minecraft.resources.ResourceLocation;
+
+public final class OverlayHud {
+    private static final ResourceLocation COMPASS_LAYER = ResourceLocation.fromNamespaceAndPath("clientirc", "compass");
+    private static final ResourceLocation WATERMARK_LAYER = ResourceLocation.fromNamespaceAndPath("clientirc", "watermark");
+
+    private static final int COMPASS_WIDTH = 180;
+    private static final int COMPASS_HEIGHT = 14;
+    private static final int COMPASS_Y = 2;
+
+    private OverlayHud() {
+    }
+
+    public static void init() {
+        HudLayerRegistrationCallback.EVENT.register(layered -> {
+            layered.attachLayerAfter(IdentifiedLayer.MISC_OVERLAYS, COMPASS_LAYER, (LayeredDraw.Layer) OverlayHud::renderCompass);
+            layered.attachLayerAfter(IdentifiedLayer.MISC_OVERLAYS, WATERMARK_LAYER, (LayeredDraw.Layer) OverlayHud::renderWatermark);
+        });
+    }
+
+    private static boolean skip(Minecraft mc) {
+        if (mc == null) {
+            return true;
+        }
+        if (mc.options != null && mc.options.hideGui) {
+            return true;
+        }
+        return mc.level == null;
+    }
+
+    private static void renderCompass(GuiGraphics graphics, DeltaTracker deltaTracker) {
+        Minecraft mc = Minecraft.getInstance();
+        if (skip(mc)) {
+            return;
+        }
+        Font font = mc.font;
+
+        int x = (graphics.guiWidth() - COMPASS_WIDTH) / 2;
+        int y = COMPASS_Y;
+
+        graphics.fill(x, y, x + COMPASS_WIDTH, y + COMPASS_HEIGHT, 0x80000000);
+
+        float yaw = mc.gameRenderer.getMainCamera().getYRot();
+
+        int[] cardYaws = {180, -90, 0, 90};
+        String[] cardLabels = {"N", "E", "S", "W"};
+
+        for (int i = 0; i < cardYaws.length; i++) {
+            float delta = wrapDegrees(cardYaws[i] - yaw);
+            if (Math.abs(delta) > 90.0f) {
+                continue;
+            }
+            int px = x + 90 + (int) delta;
+            int color = Math.abs(delta) <= 5.0f ? 0xFFFFFF55 : 0xFFFFFFFF;
+            int labelWidth = font.width(cardLabels[i]);
+            graphics.drawString(font, cardLabels[i], px - labelWidth / 2, y + 3, color, true);
+        }
+
+        graphics.fill(x + 89, y + 11, x + 92, y + 14, 0xFFFFFFFF);
+    }
+
+    private static void renderWatermark(GuiGraphics graphics, DeltaTracker deltaTracker) {
+        Minecraft mc = Minecraft.getInstance();
+        if (skip(mc)) {
+            return;
+        }
+        Font font = mc.font;
+        int x = 4;
+        int y = 4;
+        int lineHeight = font.lineHeight + 2;
+
+        String nick = resolveNick(mc);
+        int fps = mc.getFps();
+        int ping = resolvePing(mc);
+
+        graphics.drawString(font, nick, x, y, 0xFFFFFFFF, true);
+        graphics.drawString(font, "FPS: " + fps, x, y + lineHeight, 0xFFFFFFFF, true);
+        graphics.drawString(font, "Ping: " + ping + " ms", x, y + 2 * lineHeight, 0xFFFFFFFF, true);
+    }
+
+    private static String resolveNick(Minecraft mc) {
+        if (mc.player != null) {
+            GameProfile profile = mc.player.getGameProfile();
+            if (profile != null && profile.name() != null && !profile.name().isBlank()) {
+                return profile.name();
+            }
+        }
+        if (mc.getUser() != null) {
+            String name = mc.getUser().getName();
+            if (name != null && !name.isBlank()) {
+                return name;
+            }
+        }
+        return "—";
+    }
+
+    private static int resolvePing(Minecraft mc) {
+        if (mc.getConnection() == null || mc.getUser() == null) {
+            return 0;
+        }
+        PlayerInfo info = mc.getConnection().getPlayerInfo(mc.getUser().getProfileId());
+        return info == null ? 0 : info.getLatency();
+    }
+
+    private static float wrapDegrees(float v) {
+        v = v % 360.0f;
+        if (v >= 180.0f) {
+            v -= 360.0f;
+        }
+        if (v < -180.0f) {
+            v += 360.0f;
+        }
+        return v;
+    }
+}