Add debug logging for checkout and LogoutOnUnload

Add console logs to track:
- When isCheckingOut flag is set in checkout button
- When LogoutOnUnload handleUnload is called
- Whether isCheckingOut flag is detected
- When redirecting to Stripe URL

This helps diagnose why cart is still being cleared during checkout.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

src/components/LogoutOnUnload.tsx

@@ -16,11 +16,14 @@ export default function LogoutOnUnload() {
       // Don't logout if we're in the middle of checkout (navigating to Stripe)
       // The checkout component sets this flag before making the API call
       const isCheckingOut = typeof window !== 'undefined' && sessionStorage.getItem('isCheckingOut');
+      console.log('LogoutOnUnload handleUnload called, isCheckingOut flag:', isCheckingOut);
       if (isCheckingOut) {
+        console.log('Skipping logout because isCheckingOut is set');
         return;
       }
 
       // Clear cart on logout
+      console.log('Clearing cart and logging out');
       clearCart();
       // Use sendBeacon to reliably send logout even when page is closing
       // This doesn't wait for a response, which is fine for logout