Sam

Introduce mpsc::Receiver peek

3

This PR introduces a `peek` method to the `mpsc::Receiver`. This allows consumers to inspect the next message in the queue without removing it, enabling use cases that require lookahead behavior....

Restructured `ErrorKind` into `FundamentalError`, `ValidationError`, and `ThirdPartyError` enums.

Add non-breaking error category API

4

Answering the question: "was this failure a validation error or something else?" should be trivial for downstream consumers. ```Rust #[derive(Copy, Clone, Debug, Eq, PartialEq)] pub enum ErrorCategory { Fundamental, Validation,...