feat: add email settings management

- Introduced EmailSettings component for managing SMTP services.
- Added API endpoints for organization email services including CRUD operations.
- Created database migrations for organization_email_settings and organization_email_services tables.
- Updated the settings page to include EmailSettings component.
- Implemented validation and error handling for email service operations.

web/studio/src/app/settings/page.tsx

@@ -1,6 +1,7 @@
 "use client";
 
 import BrandingSettings from "@/components/BrandingSettings";
+import EmailSettings from "@/components/EmailSettings";
 import ExerciseFeatureSettings from "@/components/ExerciseFeatureSettings";
 import PageLayout from "@/components/PageLayout";
 import { useAuth } from "@/context/AuthContext";
@@ -28,6 +29,7 @@ export default function SettingsPage() {
         >
             <div className="space-y-8">
                 <BrandingSettings />
+                <EmailSettings />
                 <ExerciseFeatureSettings />
             </div>
         </PageLayout>