feat: implement comprehensive error system with categorization and recovery mechanisms #72

- Add ErrorHandler struct with comprehensive error management
- Implement categorize_error() for detailed error classification
- Add generate_detailed_error_message() for user-friendly messages
- Create handle_error_recovery() with recovery strategies
- Implement emit_error_event() for error logging and monitoring
- Add log_error_details() for debugging and analysis
- Create get_error_recovery_strategy() for recovery planning
- Implement validate_error_context() for context validation
- Add get_error_analytics() for error statistics and monitoring
- Create ErrorSeverity, ErrorCategory, and RecoveryStrategy enums
- Add ErrorContext and DetailedError structures for rich error data
- Implement comprehensive error categorization (UserOperation, Oracle, Validation, System, etc.)
- Add recovery strategies (Retry, RetryWithDelay, AlternativeMethod, Skip, Abort, ManualIntervention, NoRecovery)
- Integrate with existing event system for error logging
- Add comprehensive test coverage (5/5 tests passing)
- All 86 tests passing with no regressions

This implementation provides detailed error categorization, recovery mechanisms,
comprehensive error logging, and user-friendly error messages while maintaining
full compatibility with the existing contract architecture.

Author: 1nonlypiece