Draw the navigation rail without Tailwind

Plan step 36 (navigation group, second batch): <x-navigation-rail>'s,
<x-navigation-rail-item>'s and <x-navigation-rail-section>'s class
lists move into navigation-rail.css, navigation-rail-item.css and
navigation-rail-section.css, keyed on data-md-navigation-rail (the
mode, data-md-width, data-md-align, data-md-hide-when-collapsed,
data-md-divider, data-md-fill, data-md-open), data-md-navigation-rail-
item (data-md-active) and data-md-navigation-rail-section. Every
Tailwind wrapper class in the view — the menu row's centring padding,
the FAB row, the two swapped menu glyphs, the brand's visibility —
becomes a hook the stylesheet draws instead; the menu button itself
renders the shared md-state-layer/md-focus-ring/md-touch-target
classes (N-01's pattern) since it draws its own layer on itself, not a
child. `<x-icon>` and `<x-badge>` take size and floating props instead
of size/position classes; a small data-md-navigation-icon hook (the
shared navigation-item.css) replaces the ad hoc "relative inline-flex"
wrapper a floating badge anchors to.

`rail-collapsed` (a Tailwind @custom-variant, forbidden in Phase F) is
reproduced as plain selectors, branch for branch: the three width-
independent conditions (a fixed collapsed mode; a collapsible rail the
visitor collapsed and not open; a modal rail not open) merge into one
:where() group, provably the same match set as three separate rules
since :where(A, B, C) on an element is true exactly when :where(A) or
:where(B) or :where(C) is; the four width-gated conditions stay
separate media blocks, since CSS cannot merge different `@media`
queries. Every rem length becomes px, since these are dp-based M3
tokens, not a text measure (unlike <x-pane>'s rem widths). The FAB
overrides for a rail's header — elevation 0 (N-03), morphing into an
extended FAB instead of swapping two by display (N-23) — move from
unlayered into this file's own material.components, like toolbar.css's
FAB override: fab.css's `[data-md-fab]` is one attribute, so a doubled
selector here always outranks it without needing to sit outside the
layer.

navigation.js: the arriving-indicator stylesheet and every code comment
follow the new hooks; resources/css/components/navigation.css is
deleted (nothing imports it any more) and its line in tailwind.css with
it. Behaviour is unchanged except one thing Tailwind's `rail-collapsed:`
variant could do that plain CSS in this shape cannot: it is gone for
consuming applications too, since the definition lived only in the file
this commit removes. The development skill's guidance for it is
rewritten to point at navigation-rail.css's own selectors instead of
teaching a Tailwind variant that no longer exists.

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

resources/views/components/navigation-rail-section.blade.php

@@ -17,8 +17,8 @@
     $headingId = 'navigation-section-'.substr(md5((string) $label), 0, 10);
 @endphp
 
-<div role="group" aria-labelledby="{{ $headingId }}" data-navigation-rail-section {{ $attributes }}>
-    <p id="{{ $headingId }}" data-navigation-rail-heading>{{ $label }}</p>
+<div role="group" aria-labelledby="{{ $headingId }}" data-md-navigation-rail-section {{ $attributes }}>
+    <p id="{{ $headingId }}" data-md-navigation-rail-heading>{{ $label }}</p>
 
     {{ $slot }}
 </div>