Select on [dir='rtl'] now that no build rewrites :dir()

Plan step 39 (part 4). With Tailwind gone the Workbench's Vite build
still turns every `:dir(rtl)` into a long `:lang()` list (its own CSS
minifier, not Tailwind's doing — confirmed by rebuilding and grepping
the output). Every RTL mirror rule across the eleven stylesheets that
had one now selects `:is([dir='rtl'], [dir='rtl'] *)` instead, matching
`:dir(rtl)`'s own specificity (one pseudo-class) and its inherited
"this element or a descendant of one carrying the attribute" reach; the
built CSS now keeps the selector as written (no `:lang(` or `:dir(` left).

RTL browser tests drop the `lang="ar"` workaround the old rewrite
needed (ContainmentTest's side-sheet probe, LayoutTest's shared
layoutPage() helper) and set only dir="rtl"; CarouselTest's probe
already did. Feature tests asserting the selector's literal text
(Progress, Overlay, Menu, ListDetail, Icon, Carousel) updated to match.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Qwx5USif3wFFmxtHg5U1g9

tests/Feature/Components/ListDetailTest.php

@@ -87,7 +87,7 @@ it('shows one pane below expanded and both from it, at M3\'s fixed pane widths',
         ->toContain("@media (width >= 840px) {\n            grid-template-columns: 360px minmax(0, 1fr);\n            column-gap: var(--md-sys-measurement-space300);")
         ->toContain("@media (width >= 1200px) {\n            grid-template-columns: 412px minmax(0, 1fr);")
         ->toContain("@media (width < 840px) {\n        [data-md-list-detail]:not([data-md-selected]) > [data-md-list-detail-pane='detail'],\n        [data-md-list-detail][data-md-selected] > [data-md-list-detail-pane='list'] {\n            display: none;")
-        ->toContain('[data-md-list-detail-back] [data-md-icon]:dir(rtl)')
+        ->toContain("[data-md-list-detail-back] [data-md-icon]:is([dir='rtl'], [dir='rtl'] *)")
         ->and((string) file_get_contents(__DIR__.'/../../../resources/css/all.css'))->toContain("@import './layout/list-detail.css';")
         ->and((string) file_get_contents(__DIR__.'/../../../resources/js/material.js'))->toContain("import './layout.js'");
 });