The backend-blind baseline engine.
Compact (schema-driven) encode/decode, compatibility planning that turns a
(writer schema, reader schema, descriptor) triple into IR, and the
interpreter that runs that IR. The interpreter always works, on every
platform, including those where a JIT cannot run (r[exec.interpreter-baseline]).
Like phon-ir, this crate is binding-free: it consumes descriptors and an
IR and reaches for no reflection (r[crates.engine-is-binding-free]).
Spec: docs/content/spec.md — "Compact mode", "Compatibility", "Decoding",
"Decoding untrusted input", and r[crates.concern-separation].