Treat Mealie's "no image" sentinel as a missing cover

Mealie stores the literal string "no image" in the recipe's image field when
there is no cover, so bool(recipe["image"]) reported a cover that is not
there: the check meant to catch a missing image downgraded to a warning
instead of failing. Observed on a recipe created through Mealie's own image
import, which returned image: "no image".

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tests/test_verify.py

@@ -61,6 +61,14 @@ class TestCoverImage:
         assert status_of(report, "cover_image") == "fail"
         assert report["complete"] is False
 
+    @pytest.mark.parametrize("stored", ["no image", "No Image", "  no image  ", ""])
+    def test_mealies_no_image_sentinel_fails(self, stored):
+        # Verified against Mealie 3.22: a recipe without a cover stores the
+        # string "no image", which a truthiness test reads as a cover present.
+        report = verify_recipe(complete_recipe(image=stored))
+        assert status_of(report, "cover_image") == "fail"
+        assert report["complete"] is False
+
 
 class TestSwedishContent:
     def test_english_ingredient_line_fails(self):