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
loki5512344
a822c91637
