Function classify_protocol_headers 

pub fn classify_protocol_headers<'a>(
    version_header: Option<&str>,
    method_header: Option<&str>,
    name_header: Option<&'a str>,
) -> Result<ProtocolHeaders<'a>, ClassificationError>

Validate and classify raw MCP header values.

The common path (known method and plain ASCII name) performs no allocation.

Errors

Returns ClassificationError for untrusted protocol versions, missing mandatory metadata, or malformed Base64 sentinel values.