ver. 0.293: Code review fixes — 6 repositories, 16 fixes

- ArticleRepository: SQL injection fix (addslashes→parameterized), DRY refactor topArticles/newsListArticles
- AttributeRepository: dead class_exists('\S') blocking cache/temp clear
- CategoryRepository: dead class_exists('\S') blocking SEO link generation (critical)
- BannerRepository: parameterize $today in SQL + null guard on query()
- BasketCalculator: null guard checkProductQuantityInStock + optional DI params
- PromotionRepository: null guard on $basket (production fatal)
- OrderRepository/ShopBasketController/ajax.php: explicit DI in BasketCalculator callers

614 tests, 1821 assertions (+4 new)

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

tests/Unit/Domain/Basket/BasketCalculatorTest.php

@@ -64,4 +64,25 @@ class BasketCalculatorTest extends TestCase
         $this->assertSame('3 produkty', BasketCalculator::countProductsText('3'));
         $this->assertSame('0 produktów', BasketCalculator::countProductsText('abc'));
     }
+
+    public function testCheckProductQuantityInStockReturnsFalseOnNullBasket(): void
+    {
+        $this->assertFalse(BasketCalculator::checkProductQuantityInStock(null));
+    }
+
+    public function testCheckProductQuantityInStockReturnsFalseOnEmptyBasket(): void
+    {
+        $this->assertFalse(BasketCalculator::checkProductQuantityInStock([]));
+    }
+
+    public function testValidateBasketReturnsEmptyArrayOnNull(): void
+    {
+        $this->assertSame([], BasketCalculator::validateBasket(null));
+    }
+
+    public function testValidateBasketReturnsBasketArrayAsIs(): void
+    {
+        $basket = [['product-id' => 1, 'quantity' => 2]];
+        $this->assertSame($basket, BasketCalculator::validateBasket($basket));
+    }
 }