Refactor Frackture into a modular Python package with unified API and CLI

[cto-new]

Summary

Refactor Frackture from a single script into a proper Python package with modular components, a typed engine, and a CLI. This enables better maintainability, testing, and future extension.

Details

• Introduce package structure: frackture/preprocess.py, frackture/symbolic.py, frackture/entropy.py, frackture/engine.py, frackture/models.py, frackture/cli.py, frackture/init.py, frackture/main.py
• Implement a typed FracktureEngine exposing unified APIs: compress, decompress, encrypt, decrypt, fingerprint
• Add dataclasses for structured payloads (FrackturePayload, CompressionMetadata, EncryptionMetadata, etc.) to capture version, passes, key material, and ensure determinism
• Implement optional key-based masking for encryption mode and improve error handling
• Introduce a small CLI entry point for basic encode/decode/hash flows
• Update exports in init.py and adjust imports/tests accordingly
• Improve docstrings across modules and ensure deterministic payloads via metadata

Notable impacts

• Changes are backwards-incompatible at import surface but preserve core logic and provide a maintainable API
• CLI now works for basic encode/decode/hash flows
• Payloads are structured for testing and future evolution