fix(tests): update health check test to accept unhealthy status

Update test_health_check to accept 'unhealthy' status in addition
to 'healthy' and 'degraded'. This reflects the new health check
logic where:
- healthy: database and model are both up
- degraded: database up but model not loaded
- unhealthy: database is unavailable

Author: Sakeeb91

tests/integration/test_api.py

@@ -14,8 +14,11 @@ def test_health_check(self, test_client: TestClient) -> None:
         assert response.status_code == 200
 
         data = response.json()
-        # Status can be "healthy" or "degraded" depending on database availability
-        assert data["status"] in ("healthy", "degraded")
+        # Status depends on database and model availability:
+        # - healthy: both database and model are up
+        # - degraded: database up but model not loaded
+        # - unhealthy: database unavailable
+        assert data["status"] in ("healthy", "degraded", "unhealthy")
         assert "version" in data
         assert "timestamp" in data