Add escalated notifications

[Omarelsa1125]

Describe your changes

Briefly describe the changes you made and their purpose.
Implemented end-to-end support for escalated notifications in Checkmate. This includes:

Backend: Updated Monitor and Incident schemas to support multi-tier escalation delays and track sent notifications.

Frontend: Added a UI configuration section in the monitor edit/create flow to allow users to define alert delays.

Service: Extended the notification logic to trigger delayed alerts based on the duration of an active incident.

Write your issue number after "Fixes "

Fixes #217

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• [x ] (Do not skip this or your PR will be closed) I deployed the application locally.
• [ x] (Do not skip this or your PR will be closed) I have performed a self-review and testing of my code.
• [ x] I have included the issue # in the PR.
• [x ] I have added i18n support to visible strings (instead of <div>Add</div>, use):

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

• [x ] I have not included any files that are not related to my pull request, including package-lock and package-json if dependencies have not changed
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• [x ] I made sure font sizes, color choices etc are all referenced from the theme. I don't have any hardcoded dimensions.
• [ x] My PR is granular and targeted to one specific feature.
• [x ] I ran npm run format in server and client directories, which automatically formats your code.
• [x ] I took a screenshot or a video and attached to this PR if there is a UI change.