Reach M3's 48px target from every 40px navigation control

The theme toggle and the account-menu avatar are drawn 40px and had no target
extension; both now carry `touch-target`, and the avatar's clipping moves from
the button (which would have cut the pseudo-target off) to the <img>. The rail's
hand-rolled `after:` target becomes the same utility.
Plan: docs/plans/material-3-alignment.md, step 14 (navigation N-01).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Qwx5USif3wFFmxtHg5U1g9

tests/Feature/Components/NavigationRailTest.php

@@ -22,6 +22,8 @@ it('gives the collapsible, modal and adaptive rails a menu button and the store'
         ->toContain('data-navigation-rail-menu')
         ->toContain('aria-label="Collapse navigation"')
         ->toContain('aria-expanded="true"')
+        // The 40px menu button reaches M3's 48px target through the shared utility (N-01).
+        ->toContain('touch-target')
         ->not->toContain('data-navigation-rail-scrim')
         ->not->toContain('x-trap')
         ->and((string) $this->blade('<x-navigation-rail mode="modal" />'))