Currently, Signal Forms eagerly instantiates all nodes in the form tree because `childrenMap` iterates over the `value` and creates a `FieldNode` for every property. This ensures validation side-effects are run early, but creates pure overhead for fields without validation logic unless explicitly accessed.
This commit makes `childrenMap` lazy by default, skipping materialization for children without schema logic. This is achieved by introducing `hasLogicRules()` and `anyChildHasLogic()` across the `LogicNode` hierarchy. Fields are now only instantiated when a direct read occurs via `getChild()` (which calls the new `ensureChildrenMap()`) or if their subtree requires eager evaluation due to existing validation rules.
Fixes#67212
In some cases the logic order was not preserved properly when using `apply`. In particular this occurs when some logic is registered on a child of the root, followed by an apply to the root, followed by further logic registered on a child. In this case the final registered logic wound up running before the applied logic.
This happened because `FieldPathNode` for a child path was caching its `LogicNodeBuilder` at creation time. This meant that if the parent's `LogicNodeBuilder` changed (e.g., due to an `apply` call), the child would still be using the old one.
This commit fixes the issue by dynamically resolving the `LogicNodeBuilder` for a child path whenever it is accessed.
