Fix VDOM Update Collision Logic for Sparse Trees (Teleportation)

[tobiu]

The recent implementation of Disjoint VDOM Updates (Teleportation) introduced a regression where disjoint child updates can be incorrectly dropped from the update batch.

This occurs when:

1. A Parent component is updating with updateDepth > 1.
2. The Parent has at least one merged child (triggering Sparse Tree generation via mergedChildIds).
3. A Disjoint Child (Distance < ParentDepth) is updating independently in the same batch.
4. The Disjoint Child is NOT in the Parent's mergedChildIds set.

The current collision filtering logic (parentDepth > distance) deletes the Disjoint Child's update, assuming the Parent will cover it. However, because the Parent is generating a Sparse Tree (mergedChildIds is present), TreeBuilder prunes any child not in the AllowList.

Result: The Disjoint Child is deleted from the batch AND pruned from the Parent payload, leading to a lost update (e.g., Loading Mask failing to show).

The fix is to refine the collision detection in src/mixin/VdomLifecycle.mjs to check if the Parent is excluding the Child (Sparse Mode) before deleting the disjoint update.