fix(tests): warm up liveness endpoint before timing to fix flaky 3.10 CI

test_health_live_is_fast timed the first request through the Starlette
TestClient, which pays one-time route/client initialization cost and
measured 0.15s on a slow Python 3.10 runner (threshold 0.1s). Add a
warmup request so the assertion measures steady-state latency, matching
the endpoint's own <500ms target. No production code change.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

tests/unit/test_server.py

@@ -55,6 +55,11 @@ class TestHealthEndpoint:
         """Test liveness endpoint returns quickly."""
         import time
 
+        # Warm up once so the timed call measures steady-state latency rather
+        # than one-time TestClient/route initialization (which can exceed the
+        # threshold on slow CI runners and cause flaky failures).
+        client.get("/health/live")
+
         start = time.time()
         response = client.get("/health/live")
         duration = time.time() - start