Reduce code duplication across codebase

[arkavo-com]

Summary

SonarCloud analysis shows 5.0% duplicated lines on new code. This technical debt should be addressed to improve maintainability.

Duplication by Directory

Directory	Duplication %	Duplicated Lines
OpenTDFKit	4.4%	308
OpenTDFKitCLI	6.8%	124
xtest	14.1%	34
OpenTDFKitProfiler	0.0%	0
.github/workflows	0.0%	0
Package.swift	0.0%	0

Areas to investigate

1. OpenTDFKit (308 lines) - Likely candidates:

   • Crypto operations across TDF/NanoTDF implementations
   • Key derivation code in KeyStore/CryptoHelper
   • Similar encryption/decryption patterns

2. OpenTDFKitCLI (124 lines) - Likely candidates:

   • Command handling patterns
   • Environment variable parsing
   • File I/O operations

3. xtest (34 lines) - Lower priority, test/integration code

Suggested approach

• Run SonarCloud locally to identify specific duplicated blocks
• Extract common crypto patterns into shared utilities
• Create protocol extensions for repeated patterns
• Consider builder/factory patterns for similar object construction

Acceptance criteria

• Reduce overall duplication to < 3%
• No duplication in new code contributions
• Maintain or improve test coverage