refactor: deduplicate

lib/mixins/library_tab_focus_mixin.dart

@@ -0,0 +1,34 @@
+import 'package:flutter/material.dart';
+
+/// Mixin that provides focus management for library tabs.
+/// Handles the lifecycle of a focus node for the first item and provides
+/// a method to request focus on that item.
+mixin LibraryTabFocusMixin<T extends StatefulWidget> on State<T> {
+  /// Focus node for the first item (for programmatic focus)
+  late final FocusNode firstItemFocusNode;
+
+  /// Debug label for the focus node
+  String get focusNodeDebugLabel;
+
+  /// Number of items in the list/grid
+  int get itemCount;
+
+  @override
+  void initState() {
+    super.initState();
+    firstItemFocusNode = FocusNode(debugLabel: focusNodeDebugLabel);
+  }
+
+  @override
+  void dispose() {
+    firstItemFocusNode.dispose();
+    super.dispose();
+  }
+
+  /// Focus the first item in the grid/list (for tab activation)
+  void focusFirstItem() {
+    if (itemCount > 0) {
+      firstItemFocusNode.requestFocus();
+    }
+  }
+}