feat: Implement comprehensive Testing Architecture Enhancement

Establishes robust testing framework with clean architecture patterns:

## Phase 1: Test Infrastructure Foundation
- Global test configuration with pytest.ini and conftest.py
- Isolated test workspaces and environment management
- Comprehensive fixture library for all test types
- Test requirements and dependency management

## Phase 2: Advanced Testing Patterns
- Test builders using builder pattern for domain objects
- Mock factories for repositories, services, and configs
- API response builders for external system simulation
- Enhanced unit tests with proper mocking and isolation

## Phase 3: Test Performance and Quality
- Performance testing framework with benchmarks
- Memory usage monitoring and leak detection
- Custom assertions for domain-specific validation
- Parametrized testing for comprehensive coverage

## Phase 4: CI/CD Integration
- GitHub Actions workflow for automated testing
- Multi-stage testing: unit → integration → e2e → performance
- Code quality checks with flake8, mypy, black, isort
- Security scanning with safety and bandit

## Testing Architecture Benefits
✅ 100+ new test infrastructure components
✅ Standardized test organization (unit/integration/e2e)
✅ Mock-based testing with no external dependencies
✅ Performance regression detection
✅ Comprehensive fixture library
✅ CI/CD pipeline with quality gates

The testing framework supports the domain logic separation and provides
a solid foundation for maintaining high code quality as the system evolves.

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

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

tests/requirements-test.txt

@@ -0,0 +1,45 @@
+# Testing framework dependencies
+pytest>=7.4.0
+pytest-asyncio>=0.21.0
+pytest-cov>=4.1.0
+pytest-mock>=3.11.0
+pytest-xdist>=3.3.0
+pytest-timeout>=2.1.0
+pytest-benchmark>=4.0.0
+
+# Property-based testing
+hypothesis>=6.82.0
+
+# HTTP mocking
+aioresponses>=0.7.4
+responses>=0.23.0
+
+# Contract testing
+pact-python>=2.0.0
+
+# Mutation testing
+mutmut>=2.4.0
+
+# Test data generation
+factory-boy>=3.3.0
+faker>=19.0.0
+
+# Performance monitoring
+psutil>=5.9.0
+
+# Code quality
+flake8>=6.0.0
+black>=23.0.0
+isort>=5.12.0
+mypy>=1.4.0
+
+# Test reporting
+pytest-html>=3.2.0
+coverage[toml]>=7.2.0
+
+# Database testing
+pytest-postgresql>=5.0.0
+pytest-sqlite>=0.5.0
+
+# Async utilities
+anyio>=3.7.0