yo-han/Home-Assistant-Carelink

AI Summary: This issue proposes moving the `is_data_stale()` function out of `const.py` because it performs runtime calculations rather than being a static constant. The goal is to keep `const.py` clean and dedicated to true constants. Suggested new locations include a `helpers.py` file or inlining it directly into `sensor.py` / `binary_sensor.py` where it's already used.