fix(loaders): coerce combatant level with Pydantic-consistent rules

Feat resolution read level with an isinstance(int) check and fell back
to 1, while Pydantic accepts numeric strings and lossless floats: a
level-4 sheet authored as "4" got Toughness for level 1. _parse_level
now runs the value through TypeAdapter(int) (same lax coercion as the
model) and raises CombatantLoadError for values the model would reject.

tests/test_combatant_loader.py

@@ -146,6 +146,28 @@ class TestFeatures:
         c = load_combatant(_write(tmp_path, data))
         assert c.features[0].effects == toughness(7).effects
 
+    def test_toughness_numeric_string_level(self, tmp_path: Path) -> None:
+        data = _minimal_payload(level="4", features=["Toughness"])
+        c = load_combatant(_write(tmp_path, data))
+        assert c.level == 4
+        assert c.features[0].effects == toughness(4).effects
+
+    def test_toughness_lossless_float_level(self, tmp_path: Path) -> None:
+        data = _minimal_payload(level=4.0, features=["Toughness"])
+        c = load_combatant(_write(tmp_path, data))
+        assert c.level == 4
+        assert c.features[0].effects == toughness(4).effects
+
+    def test_non_numeric_level_raises(self, tmp_path: Path) -> None:
+        data = _minimal_payload(level="abc", features=["Toughness"])
+        with pytest.raises(CombatantLoadError, match="level must be an integer"):
+            load_combatant(_write(tmp_path, data))
+
+    def test_fractional_level_raises(self, tmp_path: Path) -> None:
+        data = _minimal_payload(level=4.5, features=["Toughness"])
+        with pytest.raises(CombatantLoadError, match="level must be an integer"):
+            load_combatant(_write(tmp_path, data))
+
     def test_level_default_one(self, tmp_path: Path) -> None:
         data = _minimal_payload(level=1, features=["Toughness"])
         c = load_combatant(_write(tmp_path, data))