Cycle 0009 (Walking skeleton milestone, issue #6): a post-run pure-function
reduction over the recorded pip-equity + exposure streams into summary metrics
(total pips, peak-to-trough drawdown, exposure sign-flip count) plus a
caller-supplied RunManifest (commit, params, data-window, seed, broker), paired
as RunReport with canonical hand-rolled zero-dep JSON (C14). Lives in a new
aura-engine report module; no engine/Harness/node-contract change.
The reduction is post-run, not a node (C8 caps a node at one record per eval
with no end-of-run eval); matches C18's manifest+metrics-per-run-from-day-one.
The `aura run` subcommand that prints the report is deferred to #8.
Grounding-check PASS (all load-bearing assumptions ratified by green tests /
authoritative sources). Spec-validation parse pass is a documented no-op (no
parser configured for the profile).
refs #6
Brummel
bf72924db7