Add recipe versioning: auto-bump on change, history sub-page

Each time the recipe name or spices are changed on the product edit
page, a new version is created instead of overwriting the current one.
Unchanged saves are skipped. A 'Rezept-Versionen' button opens a
sub-page (/produkt/{id}/rezept-versionen) listing all versions with
their spices and timestamps; the active version is highlighted in green.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/Filament/User/Resources/ProductResource.php

@@ -193,9 +193,10 @@ class ProductResource extends Resource {
 
     public static function getPages(): array {
         return [
-            'index' => Pages\ListProducts::route('/'),
-            'create' => Pages\CreateProduct::route('/create'),
-            'edit' => Pages\EditProduct::route('/{record}/edit'),
+            'index'          => Pages\ListProducts::route('/'),
+            'create'         => Pages\CreateProduct::route('/create'),
+            'edit'           => Pages\EditProduct::route('/{record}/edit'),
+            'recipe-history' => Pages\RecipeHistory::route('/{record}/rezept-versionen'),
         ];
     }