Other Calendar Systems Support

### Feature Description

Currently even with different locale, DMS only supports Gregorian calendar, it would be cool to support other calendar systems (e.g., Solar Hijri, Hijri, etc).

### Use Case

It's useful for users who live in regions that use a civil calendar different from the Gregorian calendar.

### Compositor(s)

All compositors

### If Other, please specify

_No response_

### Proposed Solution

_No response_

### Alternatives/Existing Solutions

_No response_

No files, tests, or entry points are named. Start by locating the calendar and locale handling used by all compositors, then determine the project’s supported calendar data and integration boundaries. Done means users can select or receive Solar Hijri, Hijri, and other non-Gregorian calendars consistently across all compositors.

Written by the indexing model from the issue text.