Feature Request: Jalali (Solar Hijri) calendar support for date picker controls

Is your feature request related to a problem? Please describe

I would like to contribute Jalali/Solar Hijri calendar support for WPF UI date picker controls.

The goal is to provide a date picker that:

• Displays a real Jalali month calendar, rather than only formatting a Gregorian date as Jalali text.
• Supports right-to-left layout.
• Uses Saturday as the default first day of the week.
• Optionally displays Persian digits.
• Accepts Jalali date input such as 1405/04/19.
• Exposes the selected value as a normal nullable DateTime, preserving compatibility with existing ViewModels, databases, and APIs.
• Supports light and dark WPF UI themes.
• Includes Gallery examples and automated tests.

Describe the solution you'd like

Proposed API direction

I see two possible designs:

1. A dedicated JalaliDatePicker and JalaliCalendar.
2. A more general calendar-system abstraction that allows a date picker to use PersianCalendar and could later support other calendar systems.

Before implementing the public API, I would appreciate guidance on which design better fits the project architecture.

I am willing to implement the control, styles, Gallery demonstration, documentation, and tests.

Describe alternatives you've considered

No response

Additional context

No response