refactor: consolidate tests, convert comments to English, fix linting

[wasabeef]

Summary

Implemented Git interface abstraction layer with mock testing capabilities to improve test performance and maintainability.

Changes

• Added GitInterface trait with 18 operations for worktree/branch/tag management
• Implemented RealGitInterface using git2 and command-line git
• Created MockGitInterface with thread-safe state management
• Added GitScenarioBuilder for test scenario creation
• Migrated tests to use mock implementation

Results

• Test execution time: 13-15s → 0.00s (mock tests)
• Code coverage: 27.7% → 33.6% (+5.9%)
• Total tests: 152

[github-actions]

📊 CI Results

✅ All Checks Passed

📋 Coverage & Testing

• Coverage: 33.6%
• Total Tests: 152
• Security Tests: 26
• Worktree Tests: 14
• Git Operations: 23

🎯 Quality Metrics

❌ Coverage: 33.6%
✅ Linting: All clippy warnings resolved
✅ Formatting: Code properly formatted
✅ Security: Comprehensive protection validated

🚀 Build Status

• Ubuntu: ✅ Passed
• macOS: ✅ Passed
• Artifacts: ✅ Generated

📦 Test Suite Optimization

• Test Files: 40 total (28 unified)
• Structure: Consolidated and comprehensive test coverage
• Efficiency: 70% of files are unified tests

[github-actions]

📊 CI Results

✅ All Checks Passed

📋 Coverage & Testing

• Coverage: 37.8%
• Total Tests: 175
• Security Tests: 26
• Worktree Tests: 14
• Git Operations: 23

🎯 Quality Metrics

❌ Coverage: 37.8%
✅ Linting: All clippy warnings resolved
✅ Formatting: Code properly formatted
✅ Security: Comprehensive protection validated

🚀 Build Status

• Ubuntu: ✅ Passed
• macOS: ✅ Passed
• Artifacts: ✅ Generated

📦 Test Suite Optimization

• Test Files: 42 total (28 unified)
• Structure: Consolidated and comprehensive test coverage
• Efficiency: 60% of files are unified tests