Six-task plan for the cycle-0009 report surface (issue #6): module scaffold +
RunMetrics/RunManifest/RunReport types (Task 1), the pure summarize reduction
(Task 2, RED-first), the f64_field recorded-stream adapter (Task 3, RED-first),
RunReport::to_json canonical zero-dep JSON (Task 4, RED-first), an end-to-end
determinism test reusing the cycle-0007 two-sink harness (Task 5), and the full
workspace gates (Task 6). Pure-additive in a new aura-engine report module; the
re-export line grows per task so the crate compiles at every boundary.
refs #6
Brummel
cb66708d26