feat: 榜单客户端（接收包+/slsboard命令+右侧HUD）

BoardClient注册客户端入口：接收BoardSyncPayload、/slsboard deaths/mined/off切换显示、HudElementRegistry注册右侧HUD。各玩家本地状态独立，不同步。

src/main/java/com/github/zly2006/carpetslsaddition/client/BoardClient.java

@@ -0,0 +1,69 @@
+package com.github.zly2006.carpetslsaddition.client;
+
+import com.github.zly2006.carpetslsaddition.net.BoardSyncPayload;
+import com.mojang.brigadier.arguments.StringArgumentType;
+import net.fabricmc.api.ClientModInitializer;
+import net.fabricmc.api.EnvType;
+import net.fabricmc.api.Environment;
+import net.fabricmc.fabric.api.client.command.v2.ClientCommandRegistrationCallback;
+import net.fabricmc.fabric.api.client.command.v2.FabricClientCommandSource;
+import net.fabricmc.fabric.api.client.networking.v1.ClientPlayNetworking;
+import net.fabricmc.fabric.api.client.rendering.v1.hud.HudElementRegistry;
+import net.minecraft.network.chat.Component;
+import net.minecraft.resources.Identifier;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * 客户端入口：接收榜单数据、注册 /slsboard 命令、注册 HUD 渲染。
+ *
+ * <p>纯客户端功能：显示哪个榜由本地状态决定，各玩家可不同步。
+ */
+@Environment(EnvType.CLIENT)
+public class BoardClient implements ClientModInitializer {
+
+    public static final Identifier HUD_ID = Identifier.fromNamespaceAndPath("slsa", "board_hud");
+
+    @Override
+    public void onInitializeClient() {
+        // 1) 接收服务端下发的榜单数据
+        ClientPlayNetworking.registerGlobalReceiver(BoardSyncPayload.TYPE, (payload, context) -> {
+            List<BoardClientState.Entry> entries = new ArrayList<>();
+            for (BoardSyncPayload.Entry e : payload.entries()) {
+                entries.add(new BoardClientState.Entry(e.name(), e.score()));
+            }
+            context.client().execute(() -> BoardClientState.setBoard(payload.board(), entries));
+        });
+
+        // 2) /slsboard 命令（纯客户端，非 OP 也能用）
+        ClientCommandRegistrationCallback.EVENT.register((dispatcher, registryAccess) -> {
+            dispatcher.register(
+                    net.minecraft.commands.Commands.literal("slsboard")
+                            .then(net.minecraft.commands.Commands.literal("deaths")
+                                    .executes(c -> { BoardClientState.toggle("deaths"); feedback(c.getSource()); return 1; }))
+                            .then(net.minecraft.commands.Commands.literal("mined")
+                                    .executes(c -> { BoardClientState.toggle("mined"); feedback(c.getSource()); return 1; }))
+                            .then(net.minecraft.commands.Commands.literal("off")
+                                    .executes(c -> { BoardClientState.set(""); feedback(c.getSource()); return 1; }))
+                            .then(net.minecraft.commands.Commands.argument("board", StringArgumentType.word())
+                                    .suggests((c, b) -> net.minecraft.commands.SharedSuggestionProvider.suggest(
+                                            new String[]{"deaths", "mined", "off"}, b))
+                                    .executes(c -> {
+                                        String v = StringArgumentType.getString(c, "board");
+                                        BoardClientState.set("off".equals(v) ? "" : v);
+                                        feedback(c.getSource());
+                                        return 1;
+                                    }))
+            );
+        });
+
+        // 3) HUD 渲染
+        HudElementRegistry.addLast(HUD_ID, new BoardHudElement());
+    }
+
+    private static void feedback(FabricClientCommandSource source) {
+        String d = BoardClientState.displaying;
+        source.sendFeedback(Component.literal("[SLSA] 榜单显示：" + (d.isEmpty() ? "关闭" : d)));
+    }
+}

src/main/java/com/github/zly2006/carpetslsaddition/client/BoardClientState.java

@@ -0,0 +1,58 @@
+package com.github.zly2006.carpetslsaddition.client;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * 客户端榜单状态（纯客户端，各玩家独立，不同步）。
+ *
+ * <ul>
+ *   <li>{@link #displaying}：当前显示哪个榜（"" = 不显示）。</li>
+ *   <li>{@code deaths}/{@code mined}：从服务端收到的排行数据缓存。</li>
+ * </ul>
+ */
+public final class BoardClientState {
+
+    private BoardClientState() {}
+
+    /** 当前显示的榜："" / "deaths" / "mined"。 */
+    public static volatile String displaying = "";
+
+    private static volatile List<Entry> deaths = Collections.emptyList();
+    private static volatile List<Entry> mined = Collections.emptyList();
+
+    public record Entry(String name, int score) {}
+
+    public static void setBoard(String board, List<Entry> entries) {
+        if ("deaths".equals(board)) {
+            deaths = entries;
+        } else if ("mined".equals(board)) {
+            mined = entries;
+        }
+    }
+
+    public static List<Entry> current() {
+        return switch (displaying) {
+            case "deaths" -> deaths;
+            case "mined" -> mined;
+            default -> Collections.emptyList();
+        };
+    }
+
+    public static void toggle(String board) {
+        displaying = displaying.equals(board) ? "" : board;
+    }
+
+    public static void set(String board) {
+        displaying = board;
+    }
+
+    public static String currentTitle() {
+        return switch (displaying) {
+            case "deaths" -> "死亡榜";
+            case "mined" -> "挖掘榜";
+            default -> "";
+        };
+    }
+}

src/main/java/com/github/zly2006/carpetslsaddition/client/BoardHudElement.java

@@ -0,0 +1,70 @@
+package com.github.zly2006.carpetslsaddition.client;
+
+import net.fabricmc.api.EnvType;
+import net.fabricmc.api.Environment;
+import net.fabricmc.fabric.api.client.rendering.v1.hud.HudElement;
+import net.minecraft.client.DeltaTracker;
+import net.minecraft.client.Minecraft;
+import net.minecraft.client.gui.Font;
+import net.minecraft.client.gui.GuiGraphicsExtractor;
+import net.minecraft.network.chat.Component;
+
+import java.util.List;
+
+/**
+ * 右侧排行榜 HUD：显示死亡榜/挖掘榜的 Top N。
+ *
+ * <p>纯客户端渲染，内容来自 {@link BoardClientState}（服务端同步而来）。
+ */
+@Environment(EnvType.CLIENT)
+public class BoardHudElement implements HudElement {
+
+    private static final int LINE_H = 10;
+    private static final int PAD = 4;
+    private static final int BG = 0x80000000;       // 半透明黑
+    private static final int TITLE_COLOR = 0xFFFF55; // 黄
+    private static final int TEXT_COLOR = 0xFFFFFF;  // 白
+
+    @Override
+    public void extractRenderState(GuiGraphicsExtractor g, DeltaTracker delta) {
+        String board = BoardClientState.displaying;
+        if (board == null || board.isEmpty()) {
+            return;
+        }
+        Minecraft mc = Minecraft.getInstance();
+        if (mc.player == null || mc.options.hideGui) {
+            return;
+        }
+        List<BoardClientState.Entry> list = BoardClientState.current();
+        Font font = mc.font;
+
+        String title = BoardClientState.currentTitle();
+        int maxW = font.width(title);
+        for (BoardClientState.Entry e : list) {
+            maxW = Math.max(maxW, font.width(line(e)));
+        }
+
+        int screenW = g.guiWidth();
+        int x = screenW - maxW - PAD * 2 - 2;
+        int y = 4;
+
+        // 背景
+        int h = PAD * 2 + LINE_H * (list.size() + 1);
+        g.fill(x, y, x + maxW + PAD * 2, y + h, BG);
+
+        int ty = y + PAD;
+        g.text(font, Component.literal(title), x + PAD, ty, TITLE_COLOR);
+        ty += LINE_H;
+        for (int i = 0; i < list.size(); i++) {
+            BoardClientState.Entry e = list.get(i);
+            g.text(font, Component.literal(line(e)), x + PAD, ty, TEXT_COLOR);
+            ty += LINE_H;
+        }
+    }
+
+    private static String line(BoardClientState.Entry e) {
+        String name = e.name();
+        if (name.length() > 12) name = name.substring(0, 12);
+        return name + " " + e.score();
+    }
+}

src/main/resources/fabric.mod.json

@@ -19,6 +19,9 @@
   "entrypoints": {
     "main": [
       "com.github.zly2006.carpetslsaddition.ServerMain"
+    ],
+    "client": [
+      "com.github.zly2006.carpetslsaddition.client.BoardClient"
     ]
   },
   "accessWidener": "slsa.accesswidener",