findLogicalContainerCached method
Returns the inline container node for fragmentId using the cached
container-id + node index. O(1) on cache hit, O(n) on first lookup.
Handlers should prefer this over findLogicalContainer(root, fragmentId).
Implementation
InlineContainerNode? findLogicalContainerCached(String fragmentId) {
final containerId = findLogicalContainerId(fragmentId);
if (containerId == null) return null;
return nodeById(containerId) as InlineContainerNode?;
}