Notification centre close button does not close the popover on desktop

[Spark450]

The close button in the notification centre panel does not close the popover on desktop. The panel stays open and the button appears dead.

Reproduce on https://design.alberta.ca/components/work-side-notification-panel/ — open the notification menu item in the live preview, then click the X in the panel header. Verified in headless Chromium at 1400x1000.

The event chain fires correctly: WorkSideNotificationPanel dispatches goa:work-side-notification-panel:closePopover, WorkSideMenuItem.handleCloseNotificationPanel receives it and dispatches goa:closePopover on document.body. The popover ignores it.

WorkSideMenuItem.svelte:217 dispatches without a target in the detail:

dispatch(document.body, "goa:closePopover", {});

Popover.svelte:274 only closes when target is truthy:

const { target } = (e as CustomEvent).detail;
if (target !== _targetEl) {
  // Don't close if the target is a child popover (descendant of this popover's content)
  if (target && !isInPopoverComposedTree(target)) {
    closePopover();
  }
}

With target undefined the guard short-circuits and closePopover() never runs. Confirmed by A/B on the live site with the popover open — dispatching goa:closePopover with detail: {} leaves the panel at 500x710, dispatching it with detail: { target: document.body } collapses it to 0x0.

The other goa:closePopover dispatchers (Popover.svelte:372, DatePicker.svelte:196) all pass a target, so this is the only caller hitting the gap.

Mobile is unaffected — handleCloseNotificationPanel calls closeMobileDrawer() directly when a drawer element exists, so it never goes through the popover path.

Test coverage gap: libs/react-components/specs/work-side-menu-with-notification-popover.browser.spec.tsx clicks the close button in the mobile drawer test (line 224) but the desktop popover test never does.