feat: add approve/reject modal action to `EditSubmissionPage`

[danielhe4rt]

Extend the Filament EditSubmissionPage to include a new page action that opens a modal allowing reviewers to approve or reject a Submission for the #100DaysOfCode workflow.

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Requirements

1. New Page Action

Add a custom action to EditSubmissionPage:

• Label: Review Submission
• Icon: heroicon-o-check-circle (or similar)
• Action opens a modal (Filament Action::make()->modal())
• The modal must present a Select field:

Select::make('status')
    ->options(SubmissionStatus::class)
    ->required();

• The reviewer chooses either:

  • approved
  • rejected

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2. Modal Behavior

• On submit:

  • Update the Submission model’s status
  • Save a timestamp approved_at if applicable
  • Save the approver_id as the authenticated user.

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3. UI Notes

• Keep the modal small and focused (single field + confirm button)
• Show a success notification after the status changes

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4. Acceptance Criteria

• The page displays a new “Review Submission” action consistently beside default Filament actions.
• Clicking the action opens the modal with the status selector.
• Status updates correctly and persists in the database.
• Action is fully compatible with Filament 3 page lifecycle.