Add CSV bulk upload feature for events

[crafty-arl]

Frontend:

• Created EventCSVUpload component with file upload interface
• Download CSV template button with example format
• Real-time validation and error reporting
• Success/error status messages with detailed feedback
• Automatic event list refresh after successful import

Backend:

• Created /api/events/import-csv endpoint
• CSV parsing with support for quoted values
• Field validation (required fields, date/time formats, event types)
• Bulk event insertion with error handling per row
• Returns success count and detailed error messages

Admin Dashboard:

• Added "Import CSV" tab to Event Management
• Positioned between Create Event and Create with AI
• Auto-switches to All Events tab after successful import

CSV Format:

• Required: title, description, date (YYYY-MM-DD), time (HH:MM), location, eventType
• Optional: capacity (number), thumbnailUrl
• Supported event types: code_and_coffee, code_and_brews, hackathon, workshop, meetup

🤖 Generated with Claude Code