feat(aura-core,aura-engine,aura-cli): node-instance naming retires ParamAlias

Every blueprint node now carries a name. A primitive builder gains an optional
instance name (Sma::builder().named("fast")); when omitted it defaults to the
node's type label, ASCII-lowercased verbatim ("SMA"->"sma", "SimBroker"->
"simbroker"). param_space() is now uniformly <node>.<param> at every level
including the root (sma_cross.fast.length, exposure.scale). Fan-in
distinguishability (C9) and signature_of re-key onto the node name: two same-type
siblings both defaulting to "sma" collide and IndistinguishableFanIn fires, so
one act -- naming the legs "fast"/"slow" -- fixes both the naming collision and
the fan-in check. The index-addressed ParamAlias overlay, Composite.params, the
Composite::new 5th argument, aliases_on, and check_alias_indices are removed
(Role.name and OutField.name untouched). Ledger C9 and C23 amended.

This is why the change is correct, not merely convenient: blueprints are
value-empty (C11), so the thing that would otherwise distinguish two SMAs --
their length -- is not present at construction; identity must come from a name,
not a deferred value. Closes the #56 friction surfaced by the param-space &
sweep milestone fieldtest (a freshly-authored 2-SMA cross was unbindable and
would not bootstrap without two hand-counted ParamAlias overlays).

Two plan defects were corrected during implementation and verified:
- the three new fan-in/path tests authored sma_cross at root level, which would
  qualify to "fast.length" (root prefix is empty) and is not the nested case the
  fan-in check inspects; nesting sma_cross under a root (a shared
  sma_cross_under_root helper) restores the asserted "sma_cross.fast.length" and
  IndistinguishableFanIn{node:2};
- three cycle-0030 named-binder tests bound the real harness by the old names
  (sma_cross.fast / scale) and were migrated to the new path strings, surfaced by
  the workspace test gate.

Verified by the orchestrator: cargo build/test --workspace green (198 tests,
0 red), clippy --all-targets -D warnings clean. model_to_json emits the type
label + factory param names (node-name-independent), so sample-model.json and the
graph_model golden are byte-identical (untouched). NodeSchema gained a Default
derive (the builder default-name test constructs an empty schema). fieldtests/
are frozen non-workspace records, not migrated.

closes #56

crates/aura-engine/src/graph_model.rs

@@ -232,7 +232,7 @@ pub fn model_to_json(root: &Composite) -> String {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::{Edge, OutField, ParamAlias, Role, Target};
+    use crate::{Edge, OutField, Role, Target};
     use aura_core::{
         FieldSpec, Node, NodeSchema, PortSpec, PrimitiveBuilder, Scalar,
     };
@@ -273,7 +273,11 @@ mod tests {
     fn sma_cross() -> Composite {
         Composite::new(
             "sma_cross",
-            vec![Sma::builder().into(), Sma::builder().into(), Sub::builder().into()],
+            vec![
+                Sma::builder().named("fast").into(),
+                Sma::builder().named("slow").into(),
+                Sub::builder().into(),
+            ],
             vec![
                 Edge { from: 0, to: 2, slot: 0, from_field: 0 },
                 Edge { from: 1, to: 2, slot: 1, from_field: 0 },
@@ -283,10 +287,6 @@ mod tests {
                 targets: vec![Target { node: 0, slot: 0 }, Target { node: 1, slot: 0 }],
                 source: None,
             }],
-            vec![
-                ParamAlias { name: "fast".into(), node: 0, slot: 0 },
-                ParamAlias { name: "slow".into(), node: 1, slot: 0 },
-            ],
             vec![OutField { node: 2, field: 0, name: "out".into() }],
         )
     }
@@ -315,7 +315,6 @@ mod tests {
                 targets: vec![Target { node: 0, slot: 0 }], // price -> sma_cross role 0
                 source: Some(ScalarKind::F64),
             }],
-            vec![], // params: the interior sma_cross carries the aliases
             vec![], // output: the root ends in a sink, no re-export
         )
     }
@@ -331,7 +330,6 @@ mod tests {
                 Role { name: "a".into(), targets: vec![Target { node: 0, slot: 0 }], source: None },
                 Role { name: "b".into(), targets: vec![Target { node: 1, slot: 0 }], source: None },
             ],
-            vec![],
             vec![OutField { node: 0, field: 0, name: "v".into() }],
         )
     }
@@ -358,7 +356,6 @@ mod tests {
                 source: Some(ScalarKind::F64),
             }],
             vec![],
-            vec![],
         )
     }