Wire up remaining placeholder settings, implement menu search (v2.4.0)

- Custom dashboard, Modern plugins page, and Modern comments page
  toggles previously had no effect at all — their respective takeovers/
  redirects (DashboardTakeover, SubApps' Plugins/Comments handling,
  MenuSerializer's link rewrites) ran unconditionally regardless of the
  setting. All three now default to their previous always-on behavior
  but can actually be turned off.
- Menu search had zero implementation. Sidebar.vue now shows a real
  search box (gated on the setting) that filters both the WP-native menu
  and the Aurora nav section by title, auto-expanding matching sections.
- Removed "Modern posts table" and "Modern users page" toggles (and
  their now-empty Posts/Users settings categories) — both described a
  custom management page that was never built. A checkbox with nothing
  behind it is worse than no checkbox.

Verified all four live: dashboard/plugins/comments toggles correctly
flip between the Aurora and native experience and back; menu search
filters correctly and clears back to the full menu.

Co-Authored-By: Claude Sonnet 5 <[email protected]>

admin/src/Pages/DashboardTakeover.php

@@ -27,6 +27,13 @@ class DashboardTakeover
 
   public static function is_dashboard()
   {
+    // Settings > Dashboard > "Custom dashboard" — previously always on
+    // regardless of this setting; default true so existing installs keep
+    // their current behavior until explicitly turned off.
+    if (!Settings::get("use_custom_dashboard", true)) {
+      return false;
+    }
+
     return isset($GLOBALS["pagenow"]) && $GLOBALS["pagenow"] === "index.php";
   }
 

admin/src/Pages/SubApps.php

@@ -3,6 +3,7 @@ namespace AuroraAdmin\Pages;
 
 use AuroraAdmin\Utility\Assets;
 use AuroraAdmin\Licensing\License;
+use AuroraAdmin\Options\Settings;
 
 defined("ABSPATH") || exit();
 
@@ -111,6 +112,13 @@ class SubApps
   {
     global $pagenow;
 
+    // Settings > Comments > "Modern comments page" — previously always
+    // redirected regardless of this setting; default true so existing
+    // installs keep their current behavior until explicitly turned off.
+    if (!Settings::get("modern_comments", true)) {
+      return;
+    }
+
     if ($pagenow !== "edit-comments.php" || !current_user_can("edit_posts")) {
       return;
     }