Unlink a removed node from its parents when it was stale

[janecakemaster]

Backport of Effect-TS/effect#7535, which fixed the same line in Effect v4's AtomRegistry on Aug 30.

Summary

• Node.remove() returned early when lifetime was undefined, so it never called removeChild on the node's previousParents.
• Those parents kept a removed node in children, so canBeRemoved stayed false and they, and every node above them, stayed in registry.nodes for good.
• The fix deletes the early return. disposeLifetime() already handles an undefined lifetime, so remove() now always unlinks previousParents.

Why

invalidate() on a lazy node with no listeners calls disposeLifetime(), which clears lifetime and moves parents into previousParents without recomputing. If the node is removed before it recomputes (for example, unmount and then a parent update in the same tick), remove() hit the early return and left the parents linked to it. In our app this kept a large derived value alive after every page visit.

Validation

• pnpm vitest run packages/atom/test/Atom.test.ts -t "invalidated before removal": fails before the fix (parent node still registered), passes after.
• pnpm test --run: 8 files, 105 tests passed.
• pnpm lint: passed.
• pnpm check: passed.