Add TypeScript types for core

**Description**
Currently models lacks proper notifications support.

**Proposed solution**
Add configurable notifications with sensible defaults.

**Priority**: Low/Medium

Reconcile the title with the description first: the issue mentions TypeScript types for core, while the proposed solution describes configurable notifications in models. Locate the core models entry point and any existing notification-related tests or defaults; done should mean the intended scope is implemented with sensible defaults and covered by the relevant checks.

Written by the indexing model from the issue text.