Let an application replace the safe-area insets and dock on the bottom bar

Components read the device's safe-area insets straight from env(), which a
browser test cannot fake and an application drawing its own status strip
cannot extend. Every inset the package reads, in its CSS and its views, is
now var(--material-safe-top|bottom|left|right, env(safe-area-inset-…)):
unchanged while the variables are unset.

The app shell's --material-bottom-bar also adds
var(--material-bottom-extra, 0px), so an application that docks something on
the phone's navigation bar (an offline banner) sets its height once and the
snackbar, a fab button and the page's bottom padding clear it.

A guard test fails on any env(safe-area-inset-*) outside such a variable, and
AppShellTest's assertion on the bar height's class follows the new value.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RHoXZSHc8gGpZjFmA5fPc2

resources/views/components/bottom-sheet.blade.php

@@ -52,7 +52,7 @@
         @if (filled($title)) aria-labelledby="{{ $id }}-title" @endif
         style="--sheet-max-height: {{ $height }}"
         {{ $attributes->whereDoesntStartWith('wire:model')->except(['id', 'class'])->class([
-            'fixed inset-x-0 bottom-0 z-50 mx-auto flex max-h-(--sheet-max-height) w-full max-w-160 touch-pan-y flex-col rounded-t-corner-xl bg-surface-container-low pb-[env(safe-area-inset-bottom)] text-on-surface shadow-elevation-1',
+            'fixed inset-x-0 bottom-0 z-50 mx-auto flex max-h-(--sheet-max-height) w-full max-w-160 touch-pan-y flex-col rounded-t-corner-xl bg-surface-container-low pb-[var(--material-safe-bottom,env(safe-area-inset-bottom))] text-on-surface shadow-elevation-1',
             $attributes->get('class'),
         ]) }}
     >