fix(core): prevent incorrect transition state when transitionDuration is 0 (#691)

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Co-authored-by: JH.Lee <contact@jins.dev>

Author: 3 people

.changeset/fix-transition-duration-zero-jitter.md

@@ -0,0 +1,5 @@
+---
+"@stackflow/core": patch
+---
+
+Fix intermittent incorrect transition state when `transitionDuration` is set to 0 by ensuring `now >= eventDate` in the initial aggregate call within `dispatchEvent`.

core/src/makeCoreStore.ts

@@ -92,9 +92,10 @@ export function makeCoreStore(options: MakeCoreStoreOptions): CoreStore {
     },
     dispatchEvent(name, params) {
       const newEvent = makeEvent(name, params);
+
       const nextStackValue = aggregate(
         [...events.value, newEvent],
-        new Date().getTime(),
+        Math.max(newEvent.eventDate, new Date().getTime()),
       );
 
       events.value.push(newEvent);