Draw the tabs without Tailwind

Plan step 36 (navigation group, third and last stream): <x-tabs>'s
and <x-tab>'s class lists move into resources/css/components/tabs.css,
one commit for both since they share it. Root data-md-tabs; the bar
data-md-tabs-bar with data-md-variant/-stacked/-scrollable, holding
data-md-tab buttons (data-md-tab-content, the new data-md-tab-label
wrapping the label and badge, data-md-tab-indicator); the panel
data-md-tab-panel. The server-rendered hidden panel (N-05), the 52dp
scrollable offset (N-10), the indicator's 2dp inset (N-18), the ring
moved 2px out (N-20) and aria-current sharing the active colour
(N-21) already matched the audit; only hooks, units and layer
changed. Sizes (48/64px tab height, 90px minimum width) stay px;
spacing goes through the measurement tokens where the value matches
one (the icon-label and label-badge gaps, the panel's top padding).
Imports icon.css and badge.css for what the view renders.

Hooks renamed: data-tabs-bar, data-tab, data-tab-content,
data-tab-indicator, data-scrollable, data-stacked and the bar's
data-variant to data-md-*, updated in tabs.js (dataset.tab ->
dataset.mdTab), section-nav.blade.php (which reuses the tab bar's
hooks under its own, still-Tailwind, markup),
tests/Feature/Components/TabsTest.php and tests/Browser/BarsTest.php.

Added the owed browser test: a tab panel never flashes before Alpine
boots, read from an inline script that runs while the page is still
parsing, well before Alpine's own script (docs/plans/material-3-browser-tests.md).

This closes plan step 36: every navigation-group component is now
data-md-* and Tailwind-free; tailwind.css's Navigation block keeps
only navigation.css (the bar and rail, out of this batch's scope).

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

resources/views/components/tab.blade.php

@@ -1,13 +1,14 @@
 {{-- One tab's panel, inside `<x-tabs>`, which draws the bar from its own `tabs` list. Shown while
      its `name` is the chosen one; every panel is rendered, so switching never waits on the server.
-     `class` lands on the panel (it has `pt-6` above its content by default).
 
      The id and the `hidden` panels come from the server, not from Alpine: until Alpine boots, every
      panel would otherwise be on screen at once — four `role="tabpanel"` regions for a screen reader
-     to walk — and the tab buttons' `aria-controls` would point at nothing. `<x-tabs>` renders this
-     slot before its own view, so it cannot hand the panel anything; the panel reads the attributes
-     written on `<x-tabs>` off the component stack (Blade's `@aware` mechanism) and repeats the two
-     lines tabs.blade.php runs on them. The two must agree, so change them together. --}}
+     to walk — and the tab buttons' `aria-controls` would point at nothing (N-05). `<x-tabs>` renders
+     this slot before its own view, so it cannot hand the panel anything; the panel reads the
+     attributes written on `<x-tabs>` off the component stack (Blade's `@aware` mechanism) and
+     repeats the two lines tabs.blade.php runs on them. The two must agree, so change them together.
+
+     The panel renders `data-md-tab-panel`, drawn by resources/css/components/tabs.css. --}}
 
 @props([
     'name',
@@ -37,8 +38,9 @@
     id="{{ $tabsId }}-{{ $name }}-panel"
     aria-labelledby="{{ $tabsId }}-{{ $name }}"
     tabindex="0"
+    data-md-tab-panel
     @if ((string) $name !== (string) $initial) style="display: none" @endif
-    {{ $attributes->class(['pt-6 outline-none']) }}
+    {{ $attributes }}
 >
     {{ $slot }}
 </div>