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/electrify-tables.sql

@@ -0,0 +1,11 @@
+-- Electrify tables for Electric SQL sync
+-- This tells Electric SQL which tables to sync
+-- Run this after running migrations
+
+-- Electrify notifications table
+ALTER TABLE notifications ENABLE ELECTRIC;
+
+-- You can electrify other tables as needed:
+-- ALTER TABLE documents ENABLE ELECTRIC;
+-- ALTER TABLE logs ENABLE ELECTRIC;
+