This commit improves code organization by extracting implementation logic
from the main AB module into dedicated sub-modules:

New modules:
- PropertyRunner - Property test execution logic
- CompareRunner - Implementation comparison logic
- BenchmarkRunner - Performance benchmarking logic
- RobustRunner - Invalid input testing logic
- ModuleValidator - Module-level validation
- StructValidator - Struct consistency validation
- ConsistencyChecker - Type consistency checking
- TypeFormatter - Type display formatting
- TypespecCorrector - Typespec correction and inference

This refactoring:
- Improves maintainability by separating concerns
- Makes the codebase easier to navigate and understand
- Reduces the size of the main AB module from ~1000 to ~450 lines
- Maintains all existing functionality and APIs

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

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