🧊 feat: fix createEventEmitter dispatch, add once and reset

[ashenoooone]

Fixes #505

push dispatched with Set.forEach over the live listener set. A listener that threw killed the loop, so every listener registered after it never fired and the exception surfaced at the push call site instead of staying with the broken subscriber. Set.forEach also visits entries added during iteration, so calling subscribe inside a listener delivered the event being dispatched to the new listener. Dispatch now runs over a snapshot with each call isolated, and a listener error is rethrown through queueMicrotask so it still reaches the global handler without breaking delivery.

Added once, which unsubscribes before invoking the listener so that a throwing one does not stay subscribed forever, and which can be cancelled either by the returned function or by unsubscribe with the original reference, matching Node's EventEmitter and addEventListener with { once: true }. Added reset(event) and reset(). Split off useSubscribeEffect for subscribers that only want a side effect, since useSubscribe calls setData on every push and re-renders either way. Keyed the listener map by keyof Events instead of string, which drops the four as string casts, and declared the EventEmitterApi<Events> type that the JSDoc already pointed at but that did not exist, the way createStore does with StoreApi.

One behavior change worth calling out: a listener removed mid dispatch now receives the in flight event, where before it did not. That matches Node and the DOM and falls out of the snapshot fix. 14 tests cover the new behavior. The demo is left alone here, since it would have to use API that is not published yet and the docs site builds demos against the released package rather than the workspace one.