…(WCAG 1.3.1) (#1564)

WCAG 2.2 criterion 1.3.1 (Info and Relationships, Level A) requires that
programmatic structure matches the visual presentation so assistive
technologies can correctly expose list context and item counts.

Two violations fixed:

1. Navigation sidebar (RecentList): NavGroup (renders <section>) was a direct
   child of NavList (renders <ul>), producing <ul><section>...</section></ul>.
   HTML forbids <section> as a direct child of <ul>; screen readers could not
   announce the correct list context or item count.

   Fix: remove the NavList wrapper from NavigationRecentList. NavGroup already
   creates its own internal <ul> for its NavItem children, so the rendered
   structure is now <nav><ul>...</ul><section><ul><li>...</li></ul></section></nav>,
   which is valid and correctly exposes the list to assistive technologies.

2. Toast alert group (AppAlertGroup): AlertGroup with isToast always rendered
   <ul role="list" class="pf-v6-c-alert-group pf-m-toast"> even when empty.
   An empty element declared as a list violates 1.3.1 because it claims a list
   relationship with no list items.

   Fix: return an empty fragment when there are no alerts, consistent with the
   existing guard in WorkspaceProgress/Alert.

Assisted-by: Claude Sonnet 4.6

Signed-off-by: Oleksii Orel <oorel@redhat.com>