Add mod_menu default override with showtitle; fix a11y/FAB overlap

- Create default.php for mod_menu with showtitle support, suitable
  for sidebar and footer menu modules (simple nav list, not navbar).
- Fix accessibility toolbar overlapping theme FAB by stacking the
  a11y toggle above the FAB instead of beside it.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/media/css/template.css

@@ -17274,9 +17274,9 @@ html.a11y-pause-animations *::after {
   right: 2.5rem;
 }
 
-/* When theme FAB is present, shift a11y toolbar to sit to its right */
+/* When theme FAB is present, stack a11y toolbar above it */
 body[data-theme-fab-enabled="1"] #mokoA11yToolbar {
-  right: calc(2.5rem + 200px);
+  bottom: 3.5rem;
 }
 
 /* Toggle button */