Replace raw node input indices with compile-time parameter symbols (#4387)

* Remove the dead InputAccessor traits and the uncallable test helper built on them

* Replace raw node input indices with macro-generated parameter symbols across the editor

* Audit dynamic input index usage, converting to parameter symbols and named input position constants

* Abstract the remaining input index plumbing behind ParameterRef APIs and accessors

* Build SetInputValue messages as struct literals to keep message enums impl-free

* Delete the typed parameter markers in favor of explicit-output test introspection

* Wire the interpolation control path input per chain node type

* Return no input when a parameter symbol is read against the wrong node's parameter view

node-graph/libraries/core-types/src/lib.rs

@@ -70,3 +70,23 @@ pub trait NodeInputDecleration {
 	fn identifier() -> ProtoNodeIdentifier;
 	type Result;
 }
+
+/// Master spells this trait `NodeParameter`; our node macro emits `NodeInputDecleration`.
+pub use NodeInputDecleration as NodeParameter;
+
+/// A runtime reference to one parameter of one proto node, for heterogeneous tables and runtime-chosen parameters.
+/// Convert a symbol with `.into()`; unlike a raw index, the node identifier and index always stay paired.
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct ParameterRef {
+	pub node_identifier: ProtoNodeIdentifier,
+	pub input_index: usize,
+}
+
+impl<P: NodeParameter> From<P> for ParameterRef {
+	fn from(_: P) -> Self {
+		ParameterRef {
+			node_identifier: P::identifier(),
+			input_index: P::INDEX,
+		}
+	}
+}