[Feature] Please add the calendar week numbers


### Discussed in https://github.com/Moyf/yearly-glance/discussions/102

<div type='discussions-op-text'>

<sup>Originally posted by **Heavyplay** August 14, 2025</sup>
As titled, is it possible to add calendar week numbers so that I can be informed with information within the page window.
Thank you very much.</div>