fix(signals): move-and-clear _optimisticNodes on transition merge

[brenelz]

mergeTransitionState copied outgoing._optimisticNodes into the target without clearing the outgoing array. Since the global queue's arrays alias the active transition's after initTransition, the adoption pass in initTransition re-pushed the same entries into the target right after the merge — duplicating every node, compounding across repeated merges. Mirror the move-and-clear pattern already used for _affectsNodes.

Repro: two overlapping actions with optimistic writes; when the first resumes and writes into a signal owned by the second's transition, the merged transition held the first action's optimistic node twice.

[changeset-bot]

⚠️ No Changeset found

Latest commit: 270b1b5

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

[codspeed-hq]

Merging this PR will not alter performance

✅ 7 untouched benchmarks
⏩ 113 skipped benchmarks¹

---

_{Comparing brenelz:fix/merge-transition-optimistic-dup (270b1b5) with next (ca82433)}

Footnotes

1. 113 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩