Fix Prototype Pollution in Neo.setupClass

This ticket addresses a framework bug discovered during the migration of unit tests to Playwright. Intermittent test failures pointed to a race condition caused by prototype pollution within the Neo.setupClass method in src/Neo.mjs.

The Bug

The setupClass method was directly mutating the static config object of the class it was processing. While setupClass is gated to only run once per class, this direct mutation of a static property is unsafe in a parallel environment and caused race conditions between tests running in different workers.

The Fix

The fix ensures that setupClass operates on a deep clone of the static config object and related configDescriptors, preventing any modification of the original class definition. This was achieved by:

1. Changing cfg = ctor.config || {}; to cfg = ctor.config ? Neo.clone(ctor.config, true) : {}; to work on a clone.
2. Introducing a local currentConfigDescriptors variable to prevent direct mutation of the static ctor.configDescriptors property during the build-up phase.

This change resolves the intermittent test failures and makes the class setup process more robust and safe for concurrent environments.