feat(v3.13.0): settings live DB reads, remove Directus/Appwrite, admin stats

Settings fixes:
- MAX_SITES_PER_USER, USER_RATE_LIMIT_PER_MIN/HR now read from DB settings
  table (DB > ENV > default), so dashboard/settings changes apply without
  restart. Sync cache refreshed on every save or delete.
- /api/me reports the live DB value for max_sites_per_user.

Admin improvements:
- Admin users bypass per-user rate limiting entirely (role=admin or ADMIN_EMAILS).
- Admin Overview now shows platform stats: registered users, new users (7d),
  total user sites, available tools.

Plugin cleanup:
- Appwrite and Directus plugins removed from the active registry (8 plugins
  now: WordPress, WooCommerce, WordPress Specialist, Gitea, n8n, Supabase,
  OpenPanel, Coolify). Plugin code is retained for future re-enabling.
- Settings page plugin visibility list updated to match.

Mobile onboarding:
- Stepper steps on narrow viewports stack vertically with correct full border
  and rounded corners on each step.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

core/health.py

@@ -520,7 +520,7 @@ class HealthMonitor:
         if not self.site_manager:
             return {"healthy": False, "message": "SiteManager not available"}
 
-        # Look up site info by full_id (handles multi-word plugin types like wordpress_advanced)
+        # Look up site info by full_id (handles multi-word plugin types like wordpress_specialist)
         site_info = self._find_site_info(project_id)
         if not site_info:
             return {"healthy": False, "message": f"Site not found: {project_id}"}
@@ -547,7 +547,11 @@ class HealthMonitor:
             )
 
         # Fallback: authenticated health check for WordPress-based plugins
-        if plugin_type in ("wordpress", "wordpress_advanced", "woocommerce"):
+        if plugin_type in (
+            "wordpress",
+            "wordpress_specialist",
+            "woocommerce",
+        ):
             try:
                 import aiohttp