Add multiple events in batch

Creates multiple events in a single request for better performance.

What this endpoint does:

• Creates multiple events efficiently with optimized database queries
• Batch processes classroom creation (creates missing classrooms only once)
• Associates students and professors with events in bulk
• Sends notifications for updated events within 14 days in batches

Performance optimizations:

• Classroom caching: Reuses classroom lookups across multiple events
• Smart notifications: Groups notifications efficiently for updated events
• Rate limiting: This endpoint has enhanced rate limiting due to its resource intensity

Best practices:

• Use this endpoint when creating 5+ events to get better performance
• Group events with similar classrooms together for better caching
• Consider splitting very large batches (>100 events) into smaller chunks