feat: enhance category selection flow by adding preselection support and a select button

flutter/lib/core/ui/category_then_product_picker.dart

@@ -49,18 +49,28 @@ class CategoryThenProductPicker {
     int? preselectedCategoryId,
     Future<ProductOption?> Function(String name, int categoryId)? onCreate,
   }) async {
-    // Steg 1 — välj kategori
-    final selectedCategory = await showModalBottomSheet<AdminCategoryNode>(
-      context: context,
-      isScrollControlled: true,
-      useSafeArea: true,
-      builder: (ctx) => _CategoryPickerSheet(
-        tree: categoryTree,
-        preselectedId: preselectedCategoryId,
-        onSelected: (node) => Navigator.pop(ctx, node),
-      ),
-    );
-    if (selectedCategory == null || !context.mounted) return null;
+    AdminCategoryNode? selectedCategory;
+
+    if (preselectedCategoryId != null) {
+      // AI-föreslagen kategori — hoppa direkt till produktpickern
+      selectedCategory = _findNode(categoryTree, preselectedCategoryId);
+    }
+
+    if (selectedCategory == null) {
+      // Steg 1 — visa kategoriträd
+      if (!context.mounted) return null;
+      selectedCategory = await showModalBottomSheet<AdminCategoryNode>(
+        context: context,
+        isScrollControlled: true,
+        useSafeArea: true,
+        builder: (ctx) => _CategoryPickerSheet(
+          tree: categoryTree,
+          preselectedId: preselectedCategoryId,
+          onSelected: (node) => Navigator.pop(ctx, node),
+        ),
+      );
+      if (selectedCategory == null || !context.mounted) return null;
+    }
 
     // Samla alla kategori-IDs i den valda grenen (inkl. ättlingar)
     final categoryIds = _collectIds(selectedCategory);
@@ -319,6 +329,16 @@ class _CategoryTileState extends State<_CategoryTile> {
                 fontWeight: FontWeight.w600,
               ),
             ),
+            trailing: TextButton(
+              style: TextButton.styleFrom(
+                padding: const EdgeInsets.symmetric(horizontal: 8),
+                minimumSize: const Size(0, 32),
+                tapTargetSize: MaterialTapTargetSize.shrinkWrap,
+                visualDensity: VisualDensity.compact,
+              ),
+              onPressed: () => widget.onLeafTap(node),
+              child: const Text('Välj'),
+            ),
             onTap: () => setState(() => _expanded = !_expanded),
           ),
           if (_expanded)