Correct month after changing time zone

Editor assessment

Short and effective: 'correct month after changing time zone' uses the imperative mood, states the bug domain clearly, and stays far below any length limit, with the Co-authored-by trailer correctly formatted. The main critique is the absent scope: 'timezone' or 'calendar' seems like an obvious candidate in a scheduling app and would aid changelog grouping and log filtering. No body means the underlying cause, whether an off-by-one, UTC shifting, or DST handling, is undocumented, which is a loss for a subtle class of bug like this. Structurally valid and patch-appropriate regardless.