Refactor: Modernize budget viewer state with Signals

[The-Boyo]

I began by identifying all the places where the parent and child components relied on RxJS streams (combineLatest, subscriptions, tap, ngOnInit logic) for state.
Next, I replaced those observable streams with Angular signals, created computed() values to derive the combined budgets, and replaced side-effect subscriptions using effect().
Finally, I updated the child component to accept signal-based inputs and removed lifecycle subscriptions, cleaning up the data flow so the parent’s reactive state drives the table directly.
With signal, state becomes easier to maintain because it contains less boilerplate. Signals also provide for faster state updates because they hold real data unlike RxJs which uses streams.
Signals reduce complexity to a large extend because they are easier to maintain and update synchronously while observables on the other hand have a complex set up system that makes it hard to tell even where a change occurs.
Both state management systems can coexist because observables are push-based event streams while signals are pull-based state containers.
I have used redux and it easier for managing global and complex state and handles asynchronous data better than local state management systems such as signals but signals shine when state is simple and local. All these systems compliment each other.