Plan step 36 (navigation group, third batch): <x-theme-toggle>'s icon
button (mode="toggle"|"cycle") moves into resources/css/components/
theme-toggle.css, keyed on data-md-theme-toggle="toggle"|"cycle" and
still carrying data-md-icon-button, the hook toolbar.css matches
generically so the toggle takes a toolbar's own icon colour when
placed in one (N-13). The button renders the shared md-state-layer/
md-touch-target/md-focus-ring classes (N-01's 48px target); its
corner morphs from full to sm while pressed on the fast spatial
spring, the same motion <x-button>'s own icon buttons take.
mode="picker"|"contrast" already drew a connected group over native
radios (N-04, N-17's fix), so only its wrapper's hook needed renaming.
Hook renamed: data-theme-toggle to data-md-theme-toggle, updated in
AppBarTest.php, which carries theme-toggle's render tests.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Qwx5USif3wFFmxtHg5U1g9
