Scan for Tailwind breakpoints, and drive the shell by class in the browser

Plan steps 15-17's testing. `tests/Feature/BreakpointsTest.php` reads every
file under resources/views, resources/css and resources/js — showcase example
heredocs included — and fails on any Tailwind breakpoint prefix and on any
media query or `matchMedia` string at 40, 48, 64 or 80rem (or 640/768/1024/
1280px, or the 39.99rem that stood for "below 640"). Both scans were checked
against a deliberately reintroduced `sm:w-auto` and an 80rem query.

Every render test that asserted a `sm:`/`lg:`/`xl:` class now asserts the M3
class, the drawer's pane query is 52.5rem, and the theme script keeps
`data-rail-auto` through `wire:navigate`.

NavigationTest drives the shell at 599/600/839/840/1199/1200/1600 with the
expectation each class carries: the bar on a compact window, the 96px rail from
the medium class's first pixel, a standard rail collapsed through expanded whose
menu button widens it in place with no scrim, and the rail expanded to begin
with from large and at extra-large. (Not run here — the Browser suite is out of
scope for this stream.)

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

tests/Feature/Components/AppShellTest.php

@@ -22,7 +22,7 @@ it('draws the adaptive rail, the bar, the content region and the snackbar host',
         ->toContain('data-navigation-rail="adaptive"')
         ->toContain('data-navigation-bar')
         ->toContain('<main id="content" tabindex="-1" wire:transition.navigate')
-        ->toContain('max-lg:overflow-x-clip')
+        ->toContain('max-expanded:overflow-x-clip')
         ->toContain('The page')
         ->toContain('x-data="materialSnackbar"')
         ->toMatch('/<a\s+href="#content"\s+data-skip-link/')
@@ -91,7 +91,7 @@ it('keeps the destination at the page\'s URL current while a Livewire component
 
 it('lifts the snackbar above the bar only when there is a bar', function () {
     expect((string) $this->blade('<x-app-shell :destinations="$destinations" />', ['destinations' => shellDestinations()]))
-        ->toContain('max-sm:[--material-bottom-bar:calc(4rem+var(--material-safe-bottom,env(safe-area-inset-bottom))+var(--material-bottom-extra,0px))]')
+        ->toContain('max-medium:[--material-bottom-bar:calc(4rem+var(--material-safe-bottom,env(safe-area-inset-bottom))+var(--material-bottom-extra,0px))]')
         ->and((string) $this->blade('<x-app-shell :destinations="$destinations" />', ['destinations' => [['title' => 'Inbox', 'icon' => 'inbox', 'url' => '/inbox', 'bar' => false]]]))
         ->not->toContain('data-app-shell-bar')
         ->not->toContain('--material-bottom-bar:');