Add rate limiting for file uploads to prevent abuse

[davedumto]

Problem

No rate limiting for file uploads, allowing:

• Unlimited file uploads per user
• Potential abuse and spam
• Storage space exhaustion
• Performance degradation

Impact

• Storage costs increase
• Performance degradation
• Potential abuse
• Resource exhaustion

Solution

Implement file upload rate limiting:

• Limit uploads per user/IP
• Add file size limits
• Implement upload quotas
• Add abuse prevention

Implementation

• Use Redis for upload rate limiting
• Add file size and count limits
• Implement upload quotas per user
• Add abuse detection

Acceptance Criteria

• File upload rate limiting per user/IP
• File size limits
• Upload quotas
• Abuse prevention
• Rate limit monitoring
• Error handling for rate limits