Create Form Request Validation

Description

Create Form Request classes for validating API inputs.

Acceptance Criteria

• StoreEventRequest with validation rules
• UpdateEventRequest with partial validation
• StoreAttendanceRequest created
• Custom error messages defined
• date_time validates future dates

Implementation Steps

1. php artisan make:request StoreEventRequest
2. php artisan make:request UpdateEventRequest
3. php artisan make:request StoreAttendanceRequest
4. Define validation rules
5. Add custom error messages

Reference

• Roadmap: docs/roadmaps/Implementation_Roadmap_Backend.md Phase 3, Step 7
• Standards: backend/CLAUDE.md - Form Requests section

Related Issues

• Depends on: #3, #4 (closed), #5
• Blocks: #8, #9