docs(accordion): describe shared builder state

Author: leoafarias

docs/widget/accordion.mdx

@@ -141,7 +141,8 @@ class _AccordionSectionState extends State<_AccordionSection> {
 
 ## Item State Snapshot
 
-`NakedAccordionItemState<T>` is passed to every trigger builder:
+`NakedAccordionItemState<T>` is passed to every trigger builder and
+`itemBuilder`:
 
 - `value` → item identifier
 - `isExpanded` → whether the panel is currently open

packages/naked_ui/lib/src/naked_accordion.dart

@@ -95,7 +95,7 @@ class NakedAccordionGroupState extends NakedState {
   );
 }
 
-/// Immutable state exposed to a [NakedAccordion] trigger builder.
+/// Immutable state exposed to [NakedAccordion] builders.
 class NakedAccordionItemState<T> extends NakedState {
   /// The item's unique identifier.
   final T value;
@@ -412,6 +412,8 @@ typedef NakedAccordionTriggerBuilder<T> =
 ///
 /// The [builder] receives a [NakedAccordionItemState] that includes
 /// expansion status, constraint affordances, and interaction states.
+/// The optional [itemBuilder] receives the same state around the fully
+/// assembled trigger and panel.
 ///
 /// See also:
 /// - [NakedAccordionGroup], the container that manages accordion items.