ci: expand and raise mutation gate

pyproject.toml

@@ -117,6 +117,7 @@ markers = [
 source_paths = ["obliteratus/", "scripts/"]
 only_mutate = [
     "obliteratus/config.py",
+    "obliteratus/analysis/numerical_contracts.py",
     "scripts/check_coverage_thresholds.py",
 ]
 pytest_add_cli_args = ["--no-cov", "-q"]
@@ -124,6 +125,7 @@ pytest_add_cli_args_test_selection = [
     "tests/test_config.py",
     "tests/test_config_properties.py",
     "tests/test_coverage_thresholds.py",
+    "tests/test_numerical_contracts.py",
 ]
 mutate_only_covered_lines = true
 on_dependency_change = "rerun"