- Updated the notification provider types to include 'slack'.
- Modified API tests to handle 'slack' as a valid provider type.
- Enhanced frontend forms to display Slack-specific fields (webhook URL and channel name).
- Implemented CRUD operations for Slack providers, ensuring proper payload structure.
- Added E2E tests for Slack notification provider, covering form rendering, validation, and security checks.
- Updated translations to include Slack-related text.
- Ensured that sensitive information (like tokens) is not exposed in API responses.
