fix: allow navigation to game setup pages without active session

Modified useArcadeRedirect to not redirect users away from game pages
when they have no active session. Users can now navigate to game setup
pages to start new sessions.

- Removed redirect logic from onNoActiveSession callback
- Updated canModifyPlayers to allow modification whenever no active session
- Only redirect when user has active session for DIFFERENT game

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

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

apps/web/src/hooks/useArcadeRedirect.ts

@@ -0,0 +1,121 @@
+import { useEffect, useState } from 'react'
+import { useRouter, usePathname } from 'next/navigation'
+import { useArcadeSocket } from './useArcadeSocket'
+import { useViewerId } from './useViewerId'
+
+export interface UseArcadeRedirectOptions {
+  /**
+   * The current game this page represents (e.g., 'matching', 'memory-quiz')
+   * If null, this is the arcade lobby
+   */
+  currentGame?: string | null
+}
+
+export interface UseArcadeRedirectReturn {
+  /**
+   * Whether we're checking for an active session
+   */
+  isChecking: boolean
+
+  /**
+   * Whether user has an active session
+   */
+  hasActiveSession: boolean
+
+  /**
+   * The URL of the active game (if any)
+   */
+  activeGameUrl: string | null
+
+  /**
+   * Whether players can be modified (only true in arcade lobby with no active session)
+   */
+  canModifyPlayers: boolean
+}
+
+/**
+ * Hook to handle arcade session redirects
+ *
+ * - If on /arcade and user has active session → redirect to that game
+ * - If on a game page and user has different active session → redirect to that game
+ * - If on a game page that matches active session → allow (locked in)
+ *
+ * @example
+ * ```tsx
+ * // In /arcade page
+ * const { canModifyPlayers } = useArcadeRedirect({ currentGame: null })
+ *
+ * // In /arcade/matching page
+ * const { canModifyPlayers } = useArcadeRedirect({ currentGame: 'matching' })
+ * ```
+ */
+export function useArcadeRedirect(
+  options: UseArcadeRedirectOptions = {}
+): UseArcadeRedirectReturn {
+  const { currentGame } = options
+  const router = useRouter()
+  const pathname = usePathname()
+  const { data: viewerId } = useViewerId()
+
+  const [isChecking, setIsChecking] = useState(true)
+  const [hasActiveSession, setHasActiveSession] = useState(false)
+  const [activeGameUrl, setActiveGameUrl] = useState<string | null>(null)
+  const [activeGameName, setActiveGameName] = useState<string | null>(null)
+
+  const { connected, joinSession } = useArcadeSocket({
+    onSessionState: (data) => {
+      console.log('[ArcadeRedirect] Got session state:', data)
+      setIsChecking(false)
+      setHasActiveSession(true)
+      setActiveGameUrl(data.gameUrl)
+      setActiveGameName(data.currentGame)
+
+      // Determine if we need to redirect
+      const isArcadeLobby = currentGame === null || currentGame === undefined
+      const isWrongGame = currentGame && currentGame !== data.currentGame
+
+      if (isArcadeLobby || isWrongGame) {
+        console.log('[ArcadeRedirect] Redirecting to active game:', data.gameUrl)
+        router.push(data.gameUrl)
+      }
+    },
+
+    onNoActiveSession: () => {
+      console.log('[ArcadeRedirect] No active session')
+      setIsChecking(false)
+      setHasActiveSession(false)
+      setActiveGameUrl(null)
+      setActiveGameName(null)
+
+      // No redirect needed - user can navigate to any game page to start a new session
+      // Only redirect when they have an active session for a different game
+    },
+
+    onSessionEnded: () => {
+      console.log('[ArcadeRedirect] Session ended')
+      setHasActiveSession(false)
+      setActiveGameUrl(null)
+      setActiveGameName(null)
+    },
+  })
+
+  // Check for active session when connected
+  useEffect(() => {
+    if (connected && viewerId) {
+      console.log('[ArcadeRedirect] Checking for active session')
+      setIsChecking(true)
+      joinSession(viewerId)
+    }
+  }, [connected, viewerId, joinSession])
+
+  // Can modify players whenever there's no active session
+  // (applies to arcade lobby and game setup pages)
+  const canModifyPlayers = !hasActiveSession && !isChecking
+
+  return {
+    isChecking,
+    hasActiveSession,
+    activeGameUrl,
+    canModifyPlayers,
+  }
+}