IMarkedDay Interface

The `IMarkedDay` interface is used to highlight, annotate, or mark specific days with semantic meaning (such as events, holidays, or statuses) on the calendar.

`IMarkedDay` extends `IDefinedDay`, meaning it inherits the ability to target dates and apply basic styles. In addition, it allows you to assign a semantic `type` (like 'success' or 'error' which applies theme colors), a brief `label`, and a detailed `description` to provide context for why the day is marked.

Property	Type	Description
type?	TMarkedDayType	The semantic type of the marked day, which determines its visual color theme (e.g., 'success', 'error', 'warning', 'primary', 'secondary', 'dark', 'default').
label?	string	A short text label displayed on or near the day.
description?	string	A more detailed description of the marked day, often shown in a tooltip or details view.