fix: defer BottomNavigationScope access to build time in navigation parsers

- Wrap StacBottomNavigationBar in _BottomNavigationBarWidget to defer controller access
- Wrap StacBottomNavigationView in _BottomNavigationViewWidget to defer controller access
- Move BottomNavigationScope.of(context) calls from parse() to build() methods
- Fix timing issue where InheritedWidget was accessed before being created

The issue was that both navigation parsers were calling BottomNavigationScope.of(context)
during the parsing phase, before the BottomNavigationScope was actually created in the
widget tree by StacDefaultBottomNavigationController. This caused the controller to be
null and prevented proper communication between the navigation bar and view.

By wrapping the widgets and deferring the BottomNavigationScope access to build time,
the InheritedWidget is guaranteed to be available when needed, ensuring proper
bottom navigation functionality.

Author: Potatomonsta

packages/stac/lib/src/parsers/widgets/stac_bottom_navigation_bar/stac_bottom_navigation_bar_parser.dart

@@ -21,6 +21,17 @@ class StacBottomNavigationBarParser
 
   @override
   Widget parse(BuildContext context, StacBottomNavigationBar model) {
+    return _BottomNavigationBarWidget(model: model);
+  }
+}
+
+class _BottomNavigationBarWidget extends StatelessWidget {
+  const _BottomNavigationBarWidget({required this.model});
+
+  final StacBottomNavigationBar model;
+
+  @override
+  Widget build(BuildContext context) {
     final controller = BottomNavigationScope.of(context)?.controller;
 
     return BottomNavigationBar(

packages/stac/lib/src/parsers/widgets/stac_bottom_navigation_view/stac_bottom_navigation_view_parser.dart

@@ -17,6 +17,17 @@ class StacBottomNavigationViewParser
 
   @override
   Widget parse(BuildContext context, StacBottomNavigationView model) {
+    return _BottomNavigationViewWidget(model: model);
+  }
+}
+
+class _BottomNavigationViewWidget extends StatelessWidget {
+  const _BottomNavigationViewWidget({required this.model});
+
+  final StacBottomNavigationView model;
+
+  @override
+  Widget build(BuildContext context) {
     final controller = BottomNavigationScope.of(context)?.controller;
     if (model.children.isEmpty) return const SizedBox();
     final index = controller?.index ?? 0;