refactor(games): rework room lifecycle events and remove chess plugin

Consolidate room leave/delete event handling into RoomManager emitter,
remove redundant PLAYER_LEFT publishes from GameServer, and delete the
chess game plugin (board, types, tests) in favor of the new plugin
architecture. Add per-module CLAUDE.md files for leveling, guild-settings,
feature-flags, db, api, and panel to improve agent navigability.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

bot/index.ts

@@ -3,14 +3,8 @@ import { env } from "@shared/lib/env";
 import { join } from "node:path";
 import { initializeConfig } from "@shared/lib/config";
 import { registerDomainEventListeners } from "@shared/lib/eventWiring";
-import { gameRegistry } from "@shared/games/registry";
-import { chessPlugin } from "@shared/games/chess/plugin";
-
 import { startWebServerFromRoot } from "../api/src/server";
 
-// Register game plugins
-gameRegistry.register(chessPlugin);
-
 // Initialize config from database
 await initializeConfig();