Accordion: an expanded item that cannot collapse is missing aria-disabled #3493

Description

In a single accordion with collapsible: false (the default), activating the trigger of the expanded item does nothing. The trigger still exposes no aria-disabled, so screen readers announce an active, expanded button that cannot be collapsed.

https://github.com/chakra-ui/zag/blob/main/packages/machines/accordion/src/accordion.connect.ts#L91

Steps to reproduce

1. Render an accordion with the default props (multiple: false, collapsible: false).
2. Expand the first item.
3. Inspect its trigger, or press Enter on it again.

Expected

The WAI-ARIA accordion pattern says: "If the accordion panel associated with an accordion header is visible, and if the accordion does not permit the panel to be collapsed, the header button element has aria-disabled set to true."

Actual

The trigger has aria-expanded="true" and no aria-disabled. Pressing Enter does nothing, with no signal to assistive technology.

Observed on current main.