A unified asynchronous I/O abstraction layer for Rust. `extio` provides a single trait (`Extio`) that defines common interfaces for files, networking, databases, cloud storage, IPC, scheduling, logging, and cryptography. It is designed to enable backends and runtimes to implement consistent, pluggable I/O behaviors across different environments (local, cloud, embedded, or distributed). Features include: - File and directory operations - Cloud/object storage (put/get/delete) - HTTP, TCP, UDP, and WebSocket networking - Database queries and execution - Process execution - Message queues and pub-sub - Inter-process communication (IPC) - Time and scheduling utilities - Environment configuration - Logging and metrics collection - Cryptographic signing, verification, and secret management By default, all methods are unimplemented; users are expected to provide their own implementations depending on their runtime or backend.