Admin Tools Update: Safer Submission Management, Excel Export, and Bulk Email Improvements

Added a safe admin submission delete action.

Admins can now delete a submission while keeping the submission record for audit purposes.

Related submission documents are cleaned up explicitly, including removal from storage when they are no longer used elsewhere.

Reviews, history, and other audit-related records remain preserved.

Documents that are still referenced by active submissions or other records are protected from accidental deletion.

Admin document deletion now blocks files that are still linked to submissions.

Added support for moving an accepted submission back to Revision Requested.

This allows admins to reopen a submission when corrections are needed after acceptance.

Added a configurable Excel export for event submissions.

Admins can export submission data with filters, sorting options, and selectable columns.

The export includes submission-related information in a structured Excel format for reporting and administrative use.

Improved submission status badges across the admin interface.

Statuses now use clearer semantic colors, making it easier to distinguish accepted, revision, review, and rejected states in lists and detail views.

Improved the custom submission email workflow.

Admins can now manually select multiple submissions when sending custom emails.

The selection flow includes search and filtering, making it easier to target specific groups of submissions.

Recipient emails are deduplicated automatically, so authors do not receive duplicate messages if they are linked to multiple selected submissions.

Selected submissions are validated server-side before sending to prevent invalid or outdated targets.