feat(core/hooks): add 'useSet' hook

[sukvvon]

Overview

Add useSet hook that manages a Set as state, mirroring the useMap pattern.

• add / remove for adding and removing values
• toggle adds the value if absent, removes it if present
• setAll replaces all values in the set
• reset restores the set to its initial state
• Accepts Set<T> or T[] as initial state
• Stable action references via usePreservedCallback
• SSR-safe, 100% test coverage (16 tests)

Checklist

• Did you write the test code?
• Have you run yarn run fix to format and lint the code and docs?
• Have you run yarn run test:coverage to make sure there is no uncovered line?
• Did you write the JSDoc?

[kimyouknow]

Thanks for addition! useSet mirrors useMap nicely.

[kimyouknow]

One suggestion: the toggle implementation uses if/else — an early
return pattern would be cleaner:

const toggle = usePreservedCallback((value: T) => {
  setSet(prev => {
    const nextSet = new Set(prev);

    if (nextSet.has(value)) {
      nextSet.delete(value);
      return nextSet;
    }

    nextSet.add(value);
    return nextSet;
  });
});

Non-blocking — approved. ✅