- Add accountId to Farmer, MedicationCatalogItem, PathogenCatalogItem, AntibioticCatalogItem
- Create new /api/catalog endpoints for CUSTOMER role only
- Remove DemoDataInitializer (no more demo data generation)
- Add DefaultUserInitializer for admin user creation only
- Update repositories with accountId-based query methods
- Update CatalogService with accountId isolation and role-based access
- Update SecurityConfig: /api/catalog/** for CUSTOMER, /api/admin/** for ADMIN
- Update frontend AdministrationPage to use new /api/catalog endpoints
- Migrate existing data without accountId to first admin user
- Add AdminProfilePage component for admin to edit own data
- Add 'Stammdaten' menu item in admin navigation
- Add route /admin/stammdaten for the new page
- Use existing POST /api/portal/users endpoint to save changes
- Update session context after successful save
