Shared byte-slice utilities for the Mago toolchain.
PHP source code is binary-safe, so the toolchain handles identifiers, comments, and
string literals as &[u8] end-to-end. Diagnostic messages and human-facing logs are
UTF-8 strings, so a tiny adapter layer is needed at the display boundary. This crate
is that adapter, plus a few SIMD-accelerated byte-trimming primitives.