Retrieves detailed information about a specific event.

What this endpoint does:

• Fetches a single event with all its details
• Includes complete information about assigned students and professors
• Returns both internal IDs and external API IDs where available

Use cases:

• Displaying detailed event information in your side
• Editing event details (get current values first)
• Checking event participants before making changes
• Verifying event information after creation or updates

Error handling: Returns a 404 error if the event doesn't exist or doesn't belong to your school.