Support Configurable Calendar Systems (Jalali / Islamic / Gregorian)

Feature Request: Configurable Calendar System Support (Jalali / Islamic / Gregorian) Problem Currently, Twenty appears to couple: • UI language • locale • date formatting • calendar system This makes it difficult or impossible to support alternative calendar systems such as: • Jalali (Persian/Shamsi) • Islamic/Hijri • Other region-specific calendars At the moment, even if localization is added, the application still renders dates using the Gregorian calendar in many places. This affects the entire UI experience, including: • Record lists • Record detail sidebars • Activity timelines • Filters • Date fields • Built-in fields such as createdAt and updatedAt • Navigation and date-based UI components • Relative dates --- Proposed Solution Introduce a configurable calendar system setting, separated from language/locale preferences. Example: Possible values: This setting could be conf…