Add free/paid feature gating (Role Editor, Activity Log, DB Explorer,

Analytics, White Label, remote site switcher are paid)

- New License class is the single gate every paid feature checks —
  today it's a placeholder (any non-empty license_key counts as active)
  since there's no license server yet, but every gated feature already
  funnels through it so swapping in real remote validation later won't
  touch anything else.
- Role Editor, Activity Log, and Database Explorer stay registered/
  capability-checked as before, but render an UpgradeNotice screen
  instead of the real feature when unlicensed (and skip loading the
  real JS bundle/REST data). Menu Creator, Admin Notices, Comments,
  and Plugins stay free.
- Analytics' tracking hooks and REST endpoint, and White Label's
  favicon/rename/text-replace hooks, simply don't register without a
  license. Settings fields for both stay visible/editable either way.
- Remote site switcher gated alongside its existing capability check.
- Sidebar shows a small lock badge on locked Aurora nav items; the
  Dashboard's Analytics tab shows the same upgrade prompt when locked.
- Fixed an unrelated bug surfaced while testing Role Editor: RolesData's
  REST callback called get_editable_roles() without loading
  wp-admin/includes/user.php first, which REST requests don't get for
  free (only real wp-admin page loads do) — 500'd every time.

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

app/src/pages/settings/settingsConfig.js

@@ -42,7 +42,7 @@ export const settingsCategories = [
         type: 'text',
         label: 'Remote Site Switcher Capability',
         description:
-          'WordPress capability required to see the remote site switcher in the toolbar. Defaults to "manage_options" (admin users). Users with this capability or below will see the switcher.',
+          'Pro feature — requires a license. WordPress capability required to see the remote site switcher in the toolbar. Defaults to "manage_options" (admin users). Users with this capability or below will see the switcher.',
         placeholder: 'manage_options',
       },
       {
@@ -111,7 +111,7 @@ export const settingsCategories = [
   {
     id: 'whitelabel',
     title: 'White Label',
-    subtitle: 'Rebrand and customize interface text and icons',
+    subtitle: 'Rebrand and customize interface text and icons (Pro feature — requires a license)',
     icon: 'dashicons-tag',
     fields: [
       {
@@ -198,7 +198,7 @@ export const settingsCategories = [
   {
     id: 'analytics',
     title: 'Analytics',
-    subtitle: 'Built-in analytics and tracking settings',
+    subtitle: 'Built-in analytics and tracking settings (Pro feature — requires a license)',
     icon: 'dashicons-chart-bar',
     fields: [
       {