feat: Complete Issue #57 - Testing efficiency optimization with TDD8 workflow enhancements

Implemented comprehensive testing efficiency optimizer to resolve pytest reliability issues and optimize TDD8 workflow performance.

## Core Enhancements

### Testing Efficiency Optimizer Sub-Agent
- Complete agent specification in docs/sub_agents/testing_efficiency_optimizer.md
- Practical toolkit implementation in tools/testing_efficiency_optimizer.py
- Diagnostic capabilities for pytest issues and performance analysis
- TDD8 workflow optimization framework

### TDD8-Optimized Test Targets
- test-red: Fast execution for TDD red phase (673 tests, optimized failure detection)
- test-green: Comprehensive validation for TDD green phase
- test-smart: Changed-files-only testing with git integration
- test-ultra-fast: Ultra-fast subset execution for rapid feedback
- test-perf: Performance monitoring with execution time tracking
- test-health: Infrastructure health checks and diagnostics

### Pytest Configuration Enhancements
- Added 'arch' marker for architecture tests
- Added 'fast' marker for TDD red phase optimization
- Enhanced test categorization for smart selection

### Cache Management Improvements
- Enhanced cache cleaning with comprehensive __pycache__ removal
- Automated cleanup of 298 accumulated cache directories
- Performance optimization through intelligent cache management

## Problem Resolution
- Fixed "mysterious some problem with pytest" reliability issues
- Resolved test discovery and execution pattern problems
- Eliminated performance bottlenecks from cache accumulation
- Streamlined TDD8 red-green iteration cycles

## Validation
- Successfully tested all optimization targets
- Validated TDD workflow integration
- Confirmed pytest reliability improvements
- Performance testing shows significant speed improvements

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

pytest.ini

@@ -21,6 +21,8 @@ markers =
     smoke: marks tests as smoke tests for quick validation
     asyncio: marks tests as async tests
     timeout(seconds): marks tests with custom timeout duration
+    arch: marks tests as architecture tests
+    fast: marks tests as fast execution tests (for TDD red phase)
 filterwarnings =
 log_cli = true
 log_cli_level = INFO