Moved admin/user isolation checks and related methods from Domain and NotificationGroup models to User model for better separation of concerns. Replaced direct database queries in controllers and services with new model methods. Added methods for assigning unassigned domains/groups, searching domains, and clearing old notification logs. Updated views for improved UI consistency.
Introduces user isolation mode, allowing domains, groups, and tags to be visible only to their owners when enabled. Adds user_id fields to domains and notification_groups, updates models and controllers for isolation-aware queries, and provides admin UI and endpoints for transferring domains and groups between users (single and bulk). Includes migration, settings UI, and routes for toggling isolation mode and handling data migration.
