feat: Enhance serialization and improve code clarity

- Add Symbol type support in pack/unpack (type-only serialization)
- Improve Map/WeakMap serialization using [[key,value]] format
- Improve Set/WeakSet serialization using array format
- Remove Russian comments from codebase
- Update tests to cover new serialization features
- Fix error message formatting
- Bump version to 7.0.0-alpha.3

Author: ivansglazunov