fix: bottom nav marker custom ::marker styling (#428)

* fix(bottom-nav): replace ::marker workaround with list-style: none

The `li::marker { font-size: 0px }` Safari workaround hides the bullet
visually but preserves the "disc/bulleted" semantic, causing screen readers
to announce "Punto N di M" (VoiceOver) and "Puntato" (NVDA) before each
navigation item.

Because the `<ul>` always lives inside a `<nav>` element, Safari's
`list-style: none` exemption applies and list semantics are preserved
without the workaround. Replacing it with `li { list-style: none }`
removes the spurious "bulleted" announcement while keeping correct
list-item navigation semantics.

Fixes: #62

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* chore: changesets

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: deodorhunter

.changeset/thick-mirrors-matter.md

@@ -0,0 +1,5 @@
+---
+'@italia/bottom-nav': minor
+---
+
+Remove custom styling for li elements in nav

packages/bottom-nav/src/bottom-nav-item.scss

@@ -33,6 +33,6 @@
   --#{$prefix}icon-default: var(--#{$prefix}icon-secondary);
 }
 
-li::marker {
-  font-size: 0px;
+li {
+  list-style: none;
 }