Sweep up navigation's last data-navigation-* references

Plan step 36 (navigation group, second batch, cleanup). Every leftover
data-navigation-*, data-tall, data-hide-on-scroll, data-hidden,
data-width, data-align, data-divider, data-fill and component-level
data-open reference outside the rewritten stylesheets and views moves
to data-md-*, in the files the two component commits left alone:
tests/Feature/Components/ScaffoldTest.php (the scaffold's own rewrite
is a later batch, but it renders the bar and the rail today and asserts
their hooks); tests/Browser/NavigationTest.php, ShowcaseTest.php and
ColourProfilesTest.php (selectors only — document-level attributes,
data-rail, data-rail-auto and data-app-shell*, keep their names).
NavigationTest.php also gets the browser tests the plan owed this
group (docs/plans/material-3-browser-tests.md § Navigation): a tall
bar's vertical layout at a width where the short bar would go
horizontal; hide-on-scroll never firing while a pinned snackbar is on
screen; a narrow rail's 80px width and centred destinations; a rail
that hides when collapsed leaving the layout and coming back only
through an application's own menu button.

resources/css/components/navigation.css and its import in tailwind.css
are deleted now that nothing imports the file any more (the previous
commit's message said this already happened there; it did not — this
is where it actually lands).

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

resources/css/tailwind.css

@@ -16,6 +16,3 @@
 
 @import './tokens/theme.css';
 @import './tokens/utilities.css';
-
-/* Navigation — leaving in step 36 */
-@import './components/navigation.css';