Add selector composition example for playground usage

[narutamaaurum]

Closes #109

Summary

• show how to adapt RootState to feature state when reusing feature selectors
• update the hooks playground example to use countersSelectors.getReduxCounter
• document the selector composition pattern in the README

Validation

• npm run ci-check
• cd playground && npm run tsc

[gemini-code-assist]

Code Review

This pull request updates the documentation and a playground component to adopt feature-specific selectors, replacing direct state access with countersSelectors.getReduxCounter. It introduces an adapter pattern at the composition layer to map root state to feature state, enhancing reusability. The review feedback correctly identifies that the documentation examples are missing the RootState type import and should clarify that useSelector must be called within a React component context for technical accuracy.

[gemini-code-assist]

The code snippet uses RootState as a type annotation but does not include its import. To make the example complete and copy-pasteable, please add the import from MyTypes. Additionally, useSelector should be called within a React component context to be technically accurate.

Suggested change

	import { countersSelectors } from '../features/counters';
	import { useSelector } from '../store/hooks';
	const selectReduxCounter = (state: RootState) =>
	countersSelectors.getReduxCounter(state.counters);
	const counter = useSelector(selectReduxCounter);
	import { RootState } from 'MyTypes';
	import { countersSelectors } from '../features/counters';
	import { useSelector } from '../store/hooks';
	const selectReduxCounter = (state: RootState) =>
	countersSelectors.getReduxCounter(state.counters);
	// inside a component
	const counter = useSelector(selectReduxCounter);

[gemini-code-assist]

The code snippet uses RootState as a type annotation but does not include its import. To make the example complete and copy-pasteable, please add the import from MyTypes. Additionally, useSelector should be called within a React component context to be technically accurate.

Suggested change

	import { countersSelectors } from '../features/counters';
	import { useSelector } from '../store/hooks';
	const selectReduxCounter = (state: RootState) =>
	countersSelectors.getReduxCounter(state.counters);
	const counter = useSelector(selectReduxCounter);
	import { RootState } from 'MyTypes';
	import { countersSelectors } from '../features/counters';
	import { useSelector } from '../store/hooks';
	const selectReduxCounter = (state: RootState) =>
	countersSelectors.getReduxCounter(state.counters);
	// inside a component
	const counter = useSelector(selectReduxCounter);

[narutamaaurum]

Addressed the review note in this branch update. The selector-composition snippet now imports the root-state type explicitly and wraps the useSelector call in a small React component so the example is copy-pasteable and technically accurate.