Fix modals flickering on multiple modals open

[DlLemmA]

Problem

When multiple modals are opened using Modal.confirm, previously opened modals rerender unexpectedly due to their VNode keys changing.

The root cause is that all modals share a global mutable uuid for keys. The render function closes over this mutable variable, so previously created modals can see the updated uuid, leading to unstable keys and unnecessary remounts.

Note: Vue’s useId() cannot be used here because these modals are created imperatively, outside of component setup, which triggers a Vue warning.