fix(router): adjust type check for extra parameter in navigation

fix(import): ensure correct typing for passing markdown and imageUrl
fix(recipes): delete local image file on recipe deletion to avoid orphan files

flutter/lib/core/router/app_router.dart

@@ -71,7 +71,9 @@ final appRouterProvider = Provider<GoRouter>((ref) {
           final extra = state.extra;
           String? initialMarkdown;
           String? initialImageUrl;
-          if (extra is Map<String, dynamic>) {
+          // Use 'is Map' without type params — Dart reifies generics, so
+          // Map<String,String?> does NOT match Map<String,dynamic> at runtime.
+          if (extra is Map) {
             initialMarkdown = extra['markdown'] as String?;
             initialImageUrl = extra['imageUrl'] as String?;
           } else if (extra is String) {

flutter/lib/features/import/presentation/recipe_import_tab.dart

@@ -78,8 +78,9 @@ class _RecipeImportTabState extends ConsumerState<RecipeImportTab> {
             );
 
       if (!mounted) return;
-      // Pass both markdown and imageUrl so CreateRecipeScreen can pre-fill both.
-      context.push('/recipes/create', extra: {
+      // Explicitly typed as <String, dynamic> so the router's
+      // 'is Map<String, dynamic>' runtime check succeeds.
+      context.push('/recipes/create', extra: <String, dynamic>{
         'markdown': result.markdown,
         'imageUrl': result.imageUrl,
       });