Implement Structured Logging and Enhanced Error Handling

[alienx5499]

Summary

This PR implements structured logging and enhanced error handling for the go-akavelink project, addressing Issue #12. Adds JSON-formatted logs, custom error types, and HTTP middleware for better monitoring and debugging.

What's Added

• Structured Logging - JSON logs with request IDs, performance metrics, and audit trails
• Custom Error Types - Standardized error responses with proper HTTP status codes
• HTTP Middleware - Request logging, security events, and audit tracking
• Request Correlation - Track requests across all logs for easier debugging

Key Files

New:

• internal/logging/logger.go - Core logging implementation
• internal/errors/errors.go - Custom error types
• internal/middleware/logging.go - HTTP middleware
• test/*_test.go - Comprehensive test suite

Updated:

• cmd/server/main.go - Logging initialization
• internal/handlers/*.go - All handlers use new logging/errors
• .gitignore, go.mod - Project configuration

Example Output

Structured Log:

{
  "timestamp": "2025-10-25T17:00:00Z",
  "level": "INFO",
  "request_id": "req-12345",
  "operation": "create_bucket",
  "duration_ms": 150
}

Error Response:

{
  "error": true,
  "error_code": "BUCKET_NOT_FOUND",
  "message": "Bucket 'my-bucket' not found",
  "request_id": "req-12345"
}

Commits

1. feat: add structured logging and custom error handling packages (5:00 PM)
2. feat: implement HTTP middleware for request logging and security monitoring (6:47 PM)
3. refactor: integrate structured logging and error handling into handlers and main (8:23 PM)
4. test: add comprehensive test suite and improve project configuration (9:41 PM)

Benefits

• Better debugging with request correlation
• Consistent error responses
• Production-ready logging
• Security audit trails
• Performance monitoring

Closes #12