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/dashboard/__init__.py

@@ -13,6 +13,8 @@ from .routes import (
     # K.3: API Keys routes
     dashboard_api_keys_list,
     dashboard_api_keys_revoke,
+    # K.1: Core routes
+    dashboard_api_login,
     dashboard_api_project_detail,
     dashboard_api_projects,
     dashboard_api_stats,
@@ -22,7 +24,6 @@ from .routes import (
     dashboard_health_page,
     dashboard_health_projects_partial,
     dashboard_home,
-    # K.1: Core routes
     dashboard_login_page,
     dashboard_login_submit,
     dashboard_logout,
@@ -44,6 +45,7 @@ __all__ = [
     "get_dashboard_auth",
     "register_dashboard_routes",
     # K.1
+    "dashboard_api_login",
     "dashboard_login_page",
     "dashboard_login_submit",
     "dashboard_logout",