Modal component

Create modal component used for create/edit day, create/edit user and delete.

Look for existing UI components in the repository to understand the project's styling and structure. The modal will be used for create/edit day, create/edit user, and delete actions, so check how those features currently work. Start by creating a reusable modal component in the frontend components directory, ensuring it meets accessibility standards. Test by integrating it into one of the mentioned features.

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