Add Modulo Grid Task (#273)

* add modulo_grid dataset
* ensure the pattern is mathematical, not just spatial

---------

Co-authored-by: Andreas Koepf <andreas.koepf@provisio.com>

tests/test_modulo_grid.py

@@ -0,0 +1,37 @@
+import pytest
+
+from reasoning_gym.cognition.modulo_grid import ModuloGridConfig, ModuloGridDataset
+
+
+def test_modulo_grid():
+    """Test basic properties and solution of generated items"""
+
+    # Easy
+    config = ModuloGridConfig(seed=42, size=50, size_x=10, size_y=10, max_divisor=10, max_target=10, max_holes=1)
+    dataset = ModuloGridDataset(config)
+
+    for item in dataset:
+        assert isinstance(item, dict)
+        assert "question" in item and isinstance(item["question"], str)
+        assert "answer" in item and isinstance(item["answer"], str)
+        assert "metadata" in item
+
+        # Test the scoring
+        assert item["question"] != item["answer"]
+        assert dataset.score_answer(answer=item["answer"], entry=item) == 1.0
+        assert dataset.score_answer(answer=None, entry=item) == 0.0
+
+    # Hard
+    config = ModuloGridConfig(seed=42, size=50, size_x=25, size_y=25, max_divisor=25, max_target=25, max_holes=15)
+    dataset = ModuloGridDataset(config)
+
+    for item in dataset:
+        assert isinstance(item, dict)
+        assert "question" in item and isinstance(item["question"], str)
+        assert "answer" in item and isinstance(item["answer"], str)
+        assert "metadata" in item
+
+        # Test the scoring
+        assert item["question"] != item["answer"]
+        assert dataset.score_answer(answer=item["answer"], entry=item) == 1.0
+        assert dataset.score_answer(answer=None, entry=item) == 0.0