fix: include timezone data in runtime image

tests/test_deployment_contract.py

@@ -23,6 +23,11 @@ class DeploymentContractTest(unittest.TestCase):
         self.assertIn("COPY --from=web-builder /web/dist /app/web/dist", dockerfile)
         self.assertIn("EXPOSE 6061", dockerfile)
 
+    def test_runtime_image_includes_timezone_database_for_mysql_dsn(self):
+        dockerfile = (ROOT / "Dockerfile").read_text()
+
+        self.assertIn("RUN apk add --no-cache tzdata", dockerfile)
+
     def test_docker_context_excludes_local_artifacts(self):
         entries = {
             line.strip()