Getting stuck in Distribution Wizard when logged out during flavor installation

After creating an account in the Distribution Wizard, the user is prompted to install a flavor. If the user is somehow logged out while on the "Install Flavor" page, they become stuck in an unrecoverable state:

• They cannot go back or log in again (the DW blocks navigation)
• They cannot install a flavor because that requires admin rights, which they no longer have as a guest 

Steps to Reproduce

1. Start a fresh XWiki instance and follow the Distribution Wizard
2. Create an account when prompted
3. On the flavor installation step, get logged out (e.g. session expires, cookie conflict, or delete cookies)
4. The DW page still shows the flavor install prompt, but the user is now a guest 

The Distribution Wizard should handle session loss gracefully, either by allowing the user to log in again from within the DW, or by not requiring admin privileges for the initial flavor installation.

I haven't tested it, but I think the user can log back in by manually going to the login URL.