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/modal.blade.php

@@ -64,7 +64,7 @@
 >
     <div @class([
         'flex max-h-[inherit] flex-col overflow-y-auto rounded-corner-xl bg-surface-container-high p-6 shadow-elevation-3',
-        'max-sm:h-full max-sm:rounded-none max-sm:p-0 max-sm:pt-[env(safe-area-inset-top)]' => $fullscreen,
+        'max-sm:h-full max-sm:rounded-none max-sm:p-0 max-sm:pt-[var(--material-safe-top,env(safe-area-inset-top))]' => $fullscreen,
         $boxClass,
     ])>
         @if ($fullscreen)