Shadow Crypt Shell

Shell layer for shadow_crypt, handling main workflows and I/O operations.

This crate provides the interface layer between the command-line interface and filesystem operations, building on [shadow_crypt_core] to offer secure file encryption and decryption with filename obfuscation. It manages I/O to keep the core library focused on deterministic types and operations.

Modules are vertically sliced to separate concerns like encryption, decryption and listing.