fix(complement-race): add missing useEffect import

- Runtime error: useEffect is not defined
- Added useEffect to React imports in Provider.tsx

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

apps/web/src/arcade-games/complement-race/Provider.tsx

@@ -5,7 +5,15 @@
 
 'use client'
 
-import { createContext, useCallback, useContext, useMemo, useState, type ReactNode } from 'react'
+import {
+  createContext,
+  useCallback,
+  useContext,
+  useEffect,
+  useMemo,
+  useState,
+  type ReactNode,
+} from 'react'
 import {
   type GameMove,
   buildPlayerMetadata,