feat: chat channel system (/join /leave /channel)

- config-driven channels in config/channels.yml (global, local, staff, trade) with
  emoji, colors, prefix, radius, cooldowns, permissions and aliases
- Channel record + ChannelConfig loader wired into ConfigManager (reload supported)
- ChannelService (api) + ConcurrentHashMap-backed ChannelServiceImpl, joined in
  ServiceRegistry; default channel join treated as 'not in channel'
- JoinChannelCommand / LeaveChannelCommand / ChannelCommand (+ tab completion),
  registered in CommandManager; plugin.yml commands + permissions
- ChatEventListener routes AsyncChatEvent to the active channel: per-channel
  cooldown, local-radius viewer filtering, channel-aware renderer
- EnhancedChatRenderer supports Channel overload (emojiFor/prefixText/channelColor)
- ChannelServiceImplTest covering join/leave/permissions/aliases

src/main/java/com/loki/lochat/commands/chat/ChannelCommand.java

@@ -0,0 +1,120 @@
+package com.loki.lochat.commands.chat;
+
+import com.loki.lochat.LoChat;
+import com.loki.lochat.api.service.ChannelService;
+import com.loki.lochat.channel.Channel;
+import com.loki.lochat.commands.base.PlayerCommand;
+import com.loki.lochat.utils.format.ChatFormatter;
+
+import org.bukkit.command.Command;
+import org.bukkit.command.CommandSender;
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.List;
+import java.util.Locale;
+
+/**
+ * /channel — инфо о текущем канале со списком доступных.
+ * /channel <канал> — переключиться. /channel off — выйти.
+ * /channel list — список каналов.
+ */
+public class ChannelCommand extends PlayerCommand {
+
+    public ChannelCommand(LoChat plugin) {
+        super(plugin);
+    }
+
+    @Override
+    protected boolean executePlayerCommand(@NotNull Player player, @NotNull Command command,
+                                           @NotNull String label, @NotNull String[] args) {
+        ChannelService channels = plugin.getServiceRegistry().get(ChannelService.class);
+        if (!channels.isEnabled()) {
+            player.sendMessage(ChatFormatter.parse("&#CF6679Система каналов отключена"));
+            return true;
+        }
+
+        if (args.length == 0) {
+            showCurrent(player, channels);
+            return true;
+        }
+
+        switch (args[0].toLowerCase(Locale.ROOT)) {
+            case "off", "leave" -> {
+                if (channels.isInChannel(player)) {
+                    channels.leave(player);
+                    player.sendMessage(ChatFormatter.parse("&#9878C9Вы вышли из канала"));
+                } else {
+                    player.sendMessage(ChatFormatter.parse("&#B798A8Вы не находитесь в канале"));
+                }
+            }
+            case "list" -> listChannels(player, channels);
+            default -> joinChannel(player, channels, args[0]);
+        }
+        return true;
+    }
+
+    private void showCurrent(Player player, ChannelService channels) {
+        Channel active = channels.getActive(player).orElse(null);
+        if (active == null) {
+            Channel def = channels.getDefault();
+            player.sendMessage(ChatFormatter.parse("&#B798A8Вы в дефолтном канале [&#7858E9"
+                    + (def == null ? "?" : def.display() + "&8 " + def.prefix()) + "&#B798A8]"));
+        } else {
+            player.sendMessage(ChatFormatter.parse("&#9878C9Вы в канале [&#7858E9"
+                    + active.display() + "&8 " + active.prefix() + "&#9878C9]"));
+        }
+        player.sendMessage(ChatFormatter.parse("&#B798A8/join <канал> &#9878C9— войти, "
+                + "&#B798A8/channel list &#9878C9— все каналы"));
+    }
+
+    private void listChannels(Player player, ChannelService channels) {
+        player.sendMessage(ChatFormatter.parse("&#B798A8Доступные каналы:"));
+        for (Channel c : channels.getChannels()) {
+            boolean canUse = channels.canUse(player, c);
+            boolean active = c.equals(channels.getActive(player).orElse(null));
+            player.sendMessage(ChatFormatter.parse((canUse ? "&#9878C9" : "&#CF6679")
+                    + (active ? "\u25B8 " : "\u25AA ") + c.display() + "&8 " + c.prefix()
+                    + (canUse ? "" : " &#CF6679(нет прав)")
+                    + " &#B798A8— " + (c.isGlobalScope() ? "глобальный" : "локальный, " + c.radius() + "б")));
+        }
+    }
+
+    private void joinChannel(Player player, ChannelService channels, String name) {
+        Channel channel = channels.find(name);
+        if (channel == null) {
+            player.sendMessage(ChatFormatter.parse("&#CF6679Канал &#7858E9" + name + " &#CF6679не найден"));
+            return;
+        }
+        if (!channels.canUse(player, channel)) {
+            player.sendMessage(ChatFormatter.parse(
+                    plugin.getConfigManager().getMessagesConfig().getNoPermission()));
+            return;
+        }
+        Channel active = channels.getActive(player).orElse(null);
+        channels.join(player, channel);
+        if (channel.equals(active)) {
+            player.sendMessage(ChatFormatter.parse("&#B798A8Вы уже в канале [&#7858E9"
+                    + channel.display() + "&8 " + channel.prefix() + "&#B798A8]"));
+        } else {
+            player.sendMessage(ChatFormatter.parse("&#9878C9Вы вошли в канал [&#7858E9"
+                    + channel.display() + "&8 " + channel.prefix() + "&#9878C9]"));
+        }
+    }
+
+    @Override
+    protected @Nullable List<String> getTabCompletions(@NotNull CommandSender sender, @NotNull Command command,
+                                                       @NotNull String alias, @NotNull String[] args) {
+        if (args.length != 1) {
+            return null;
+        }
+        ChannelService channels = plugin.getServiceRegistry().get(ChannelService.class);
+        String input = args[0].toLowerCase(Locale.ROOT);
+        return java.util.stream.Stream.concat(
+                        java.util.stream.Stream.of("list", "off"),
+                        channels.getChannels().stream().map(Channel::id))
+                .filter(s -> s.startsWith(input))
+                .toList();
+    }
+}