Add architecture marker registration guard test

Co-authored-by: Shri Sukhani <shrisukhani@users.noreply.github.com>

Author: cursoragent

tests/test_pyproject_architecture_marker.py

@@ -0,0 +1,12 @@
+from pathlib import Path
+
+import pytest
+
+pytestmark = pytest.mark.architecture
+
+
+def test_pyproject_registers_architecture_pytest_marker():
+    pyproject_text = Path("pyproject.toml").read_text(encoding="utf-8")
+
+    assert 'markers = [' in pyproject_text
+    assert "architecture: architecture/guardrail quality gate tests" in pyproject_text