feat: Integrate Electric SQL for real-time notifications and enhance PostgreSQL configuration

- Added Electric SQL service to docker-compose for real-time data synchronization.
- Introduced PostgreSQL configuration for logical replication and performance tuning.
- Created scripts for initializing Electric SQL user and electrifying tables.
- Implemented notification model and service in the backend.
- Developed ElectricProvider and useNotifications hook in the frontend for managing notifications.
- Updated environment variables and package dependencies for Electric SQL integration.

scripts/docker/init-electric-user.sql

@@ -0,0 +1,23 @@
+-- Create Electric SQL replication user
+-- This script is run during PostgreSQL initialization
+
+DO $$
+BEGIN
+    IF NOT EXISTS (SELECT FROM pg_user WHERE usename = 'electric') THEN
+        CREATE USER electric WITH REPLICATION PASSWORD 'electric_password';
+    END IF;
+END
+$$;
+
+-- Grant necessary permissions
+GRANT CONNECT ON DATABASE surfsense TO electric;
+GRANT USAGE ON SCHEMA public TO electric;
+GRANT SELECT ON ALL TABLES IN SCHEMA public TO electric;
+GRANT SELECT ON ALL SEQUENCES IN SCHEMA public TO electric;
+
+-- Grant permissions on future tables
+ALTER DEFAULT PRIVILEGES IN SCHEMA public GRANT SELECT ON TABLES TO electric;
+ALTER DEFAULT PRIVILEGES IN SCHEMA public GRANT SELECT ON SEQUENCES TO electric;
+
+-- Note: Electric SQL will create its own publications automatically
+-- We don't need to create publications here