- Added `state.c` to handle saving and loading the state of the CPU and Bus.
- Implemented CRC32 checksum for data integrity verification during state operations.
- Enhanced `README.md` in tests/roms to document new test commands for decimal, interrupt, Apple I, and nestest.
- Created new test files: `run_apple1.c`, `run_decimal.c`, `run_interrupt.c`, `run_nestest.c`, and `run_vectors.c` to validate the new features.
- Updated `run_tests.c` to include tests for state saving/loading and other functionalities.
- Introduced `test_vectors.py` to facilitate downloading and running JSON test vectors for opcode verification.
andwati