Fix/maintenance recurring edit validation

[ZeinebMegaadi]

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Describe your changes

When editing a repeating maintenance window whose first occurrence has already passed, the form validation rejected the existing start date with "Start date and time must be in the future", making it impossible to save any edits.
The fix extracts the base object schema into maintenanceWindowBaseSchema and derives two schemas from it: maintenanceWindowSchema (with the future date refine, used on create) and maintenanceWindowEditSchema (without it, used on edit). Since one-time windows are auto-deleted by MongoDB's TTL index once they expire, skipping the future date check in edit mode is safe for all cases.

Write your issue number after "Fixes "

Fixes #3546

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const { t } = useTranslation();
<div>{t('add')}</div>

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[ZeinebMegaadi]

This fix happens after any edit and not specifically for repeating windows though I'm not sure if it's okay to be kept this way or if I should restrict it to only repeating windows. Do let me know!