audit: cycle 0036 — refresh stale sample cross-refs; drift-clean otherwise

Close-audit for cycle 0036 (commit range 560c2d0..94af4c7). Architect drift review
against the design ledger + CLAUDE.md: no contract drift. No regression scripts are
configured (the architect is the gate); build + test + clippy verified green.

cycle 0036 tidy (clean):
- C8/C9/C10 preserved: the enriched sample is multiply-nested composites over shipped
  primitives — multi-output is the macd composite re-exporting columns (not a >1-record
  primitive); brokers stay downstream nodes.
- C12/C19 preserved: the eight sweep axes are a bijection with the injective,
  path-qualified param_space under nesting; the bound blend.weights[2] is correctly
  absent from both the axes and the surface. The re-captured render golden, the two
  in-crate pins, and the cli_run E2E pin all carry the identical eight-tuple in lockstep.
- C14 preserved: the re-captured sample-model.json is the deterministic model of the
  enriched sample; the engine's own minimal model_golden (sample_root) is independent
  and byte-unchanged.
- C23 preserved: bind resolves the param name to a fixed position; the fixed blend
  weight is a structural constant (deform-not-tune), dropped from the tuning surface,
  and the compilat is unchanged.

Two stale cross-references found and refreshed (doc debt, no behaviour change):
- crates/aura-engine/src/graph_model.rs: sample_root's "Mirrors build_sample()
  (...:161-190)" was doubly stale — build_sample moved and the CLI sample is now the
  richer signals graph; re-grounded to state sample_root is a deliberately minimal,
  independent serializer fixture.
- crates/aura-cli/src/main.rs: sample_blueprint_with_sinks' "single source of the
  sample topology" + "SMA lengths + exposure scale" overclaimed post-enrichment;
  re-grounded to the root harness whose signal is the nested signals composite, with
  the eight free params.

crates/aura-cli/src/main.rs

@@ -209,9 +209,11 @@ fn signals(name: &str) -> Composite {
 
 /// The sample signal-quality blueprint (value-empty) **with its two recording
 /// sinks reachable**: returns the equity + exposure receivers a per-point sweep
-/// run drains (the SMA lengths + exposure scale are injected at compile via the
-/// point vector). The single source of the sample topology — `build_sample`
-/// (the `aura graph` entry) is expressed on top of it.
+/// run drains (the eight free params — the trend SMA lengths, the momentum EMA
+/// lengths, the two open blend weights, and the exposure scale — are injected at
+/// compile via the point vector). The root harness of the sample topology, whose
+/// signal is built by the nested `signals` composite; `build_sample` (the `aura
+/// graph` entry) is expressed on top of it.
 #[allow(clippy::type_complexity)]
 fn sample_blueprint_with_sinks() -> (
     Composite,

crates/aura-engine/src/graph_model.rs

@@ -302,9 +302,11 @@ mod tests {
     /// A small, stable root harness exercising the four model elements: a bound
     /// source role (`price`, → a synthetic source node), a composite reference
     /// (`sma_cross`, → a `composites` entry), a plain node (`Exposure`), and a
-    /// sink (`Recorder`, `output: vec![]`). Mirrors `build_sample()`
-    /// (aura-cli/src/main.rs:161-190); the Recorder receiver is dropped because
-    /// the model serializer never runs the graph.
+    /// sink (`Recorder`, `output: vec![]`). A deliberately minimal serializer
+    /// fixture, independent of the CLI's built-in sample (`build_sample` in
+    /// aura-cli — a richer nested `signals` graph since cycle 0036), kept small so
+    /// this golden stays stable; the Recorder receiver is dropped because the
+    /// model serializer never runs the graph.
     fn sample_root() -> Composite {
         let (tx, _rx) = mpsc::channel();
         Composite::new(