build: advertise Python 3.14 runtime in PyPI classifiers

Fixes I4 from the PR #22 coherence review. Slow E2E runs on
Python 3.13 and 3.14, and all docs say the project runs on
Python 3.12+. The classifier list previously stopped at 3.13,
which hid the project from PyPI users filtering by 3.14.

Adds a classifier test to prevent future drift.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: ayhammouda

pyproject.toml

@@ -18,6 +18,7 @@ classifiers = [
     "Intended Audience :: Developers",
     "Programming Language :: Python :: 3.12",
     "Programming Language :: Python :: 3.13",
+    "Programming Language :: Python :: 3.14",
     "Topic :: Documentation",
     "Topic :: Software Development :: Libraries",
 ]

tests/test_packaging.py

@@ -109,6 +109,13 @@ def test_required_deps_present(self):
         for dep_name in required_dep_names:
             assert dep_name in pyproject, f"Missing dependency: {dep_name}"
 
+    def test_classifiers_advertise_supported_python_versions(self):
+        """Classifiers must list every Python runtime the project supports."""
+        pyproject = (PROJECT_ROOT / "pyproject.toml").read_text()
+        for minor in (12, 13, 14):
+            classifier = f"Programming Language :: Python :: 3.{minor}"
+            assert classifier in pyproject, f"Missing classifier: {classifier}"
+
 
 class TestVersionFlag:
     """PKG-06: --version flag prints version."""