Add the rail's narrow collapsed width

Plan step 25 (navigation Missing): NavigationRailCollapsedTokens
.NarrowContainerWidth, 80dp, had no way in — only the default 96.
`<x-navigation-rail width="narrow">` takes it; the collapsed width is now a
variable, so the four rules that each have their own reason to name it follow
without a specificity fight. No label fits under a 56px indicator at 80px, so a
narrow rail's items are their icons alone, with the label taken out of the
drawing and left in the accessibility tree, where it names the destination.

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

resources/views/showcase/sections/navigation.blade.php

@@ -58,7 +58,7 @@
                 </div>
             </div>
             BLADE,
-        'Collapsed and expanded rails' => <<<'BLADE'
+        'Collapsed, narrow and expanded rails' => <<<'BLADE'
             <div class="flex w-full flex-wrap items-start gap-6">
                 <div class="flex h-[36rem] overflow-hidden rounded-corner-lg border border-outline-variant">
                     <x-navigation-rail mode="collapsed" label="Collapsed example" divider>
@@ -80,6 +80,22 @@
                     </x-navigation-rail>
                 </div>
 
+                <div class="flex h-[36rem] overflow-hidden rounded-corner-lg border border-outline-variant">
+                    <x-navigation-rail mode="collapsed" width="narrow" label="Narrow example" divider>
+                        <x-slot:header>
+                            <x-fab label="Compose" icon="edit" />
+                        </x-slot:header>
+
+                        <x-navigation-rail-item label="Inbox" icon="inbox" link="#navigation" no-wire-navigate active badge="12" />
+                        <x-navigation-rail-item label="Starred" icon="star" link="#navigation" no-wire-navigate />
+                        <x-navigation-rail-item label="Sent" icon="send" link="#navigation" no-wire-navigate />
+
+                        <x-slot:footer>
+                            <x-navigation-rail-item label="Settings" icon="settings" link="#navigation" no-wire-navigate />
+                        </x-slot:footer>
+                    </x-navigation-rail>
+                </div>
+
                 <div class="flex h-[36rem] overflow-hidden rounded-corner-lg border border-outline-variant">
                     <x-navigation-rail mode="expanded" label="Expanded example">
                         <x-slot:header>