Let the navigation bar hide on a scroll down

Plan step 25 (navigation Missing): M3's "hides on scroll-down, reappears on
scroll-up" had no implementation. `<x-navigation-bar hide-on-scroll>` slides the
bar out on the default spatial spring — an instant swap under reduced motion,
which zeroes the duration token — and never while a snackbar, a bottom sheet or
a drawer is anchored to its edge; focus reaching the bar brings it back.
`<x-app-shell hide-bar-on-scroll>` picks it, and --material-bottom-bar follows
the bar down and up so a `fab` button and the snackbar keep their offsets.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Qwx5USif3wFFmxtHg5U1g9

resources/views/components/app-shell.blade.php

@@ -55,7 +55,8 @@
      itself. The rail is one element at every width, so what is in it is also in the modal rail a
      phone opens. `label` names both navigation landmarks ("Main"); `rail-width` is the expanded
      rail's width; `tall-bar` picks M3's 80px navigation bar over the 64px one, and the bottom
-     offset every pinned thing reads follows it.
+     offset every pinned thing reads follows it; `hide-bar-on-scroll` lets the bar leave the window
+     while the page scrolls down, and `--material-bottom-bar` goes down and comes back with it.
 
      `banner` or `top` is a decision about what the bar belongs to: an application-wide bar — one
      search, one account menu, the same on every page — spans the window and the rail starts under
@@ -84,6 +85,7 @@
     'label' => null,
     'railWidth' => '16rem',
     'tallBar' => false,
+    'hideBarOnScroll' => false,
 ])
 
 @php
@@ -177,7 +179,7 @@
 
     @if ($barItems->isNotEmpty())
         <div data-app-shell-bar class="fixed inset-x-0 bottom-0 z-30 medium:hidden">
-            <x-livewire-material::navigation-bar :label="$label" :tall="$tallBar">
+            <x-livewire-material::navigation-bar :label="$label" :tall="$tallBar" :hide-on-scroll="$hideBarOnScroll">
                 @foreach ($barItems as $item)
                     <x-livewire-material::navigation-bar-item :label="$item['title']" :icon="$item['icon']" :link="$item['url']" :active="$item['active']" :badge="$item['badge']" :badge-label="$item['badgeLabel']" :no-wire-navigate="! $item['navigate']" />
                 @endforeach