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

editor/src/test_utils.rs

@@ -9,8 +9,6 @@ use crate::node_graph_executor::Instrumented;
 use crate::node_graph_executor::NodeRuntime;
 use crate::test_utils::test_prelude::LayerNodeIdentifier;
 use glam::{DVec2, UVec2};
-use graph_craft::document::DocumentNode;
-use graphene_std::InputAccessor;
 use graphene_std::raster::color::Color;
 use graphene_std::uuid::NodeId;
 
@@ -195,15 +193,6 @@ impl EditorTestUtils {
 		self.editor.dispatcher.message_handlers.portfolio_message_handler.active_document_mut().unwrap()
 	}
 
-	pub fn get_node<'a, T: InputAccessor<'a, DocumentNode>>(&'a self) -> impl Iterator<Item = T> + 'a {
-		self.active_document()
-			.network_interface
-			.document_network()
-			.recursive_nodes()
-			.inspect(|(_, node, _)| println!("{:#?}", node.implementation))
-			.filter_map(move |(_, document, _)| T::new_with_source(document))
-	}
-
 	pub async fn move_mouse(&mut self, x: f64, y: f64, modifier_keys: ModifierKeys, mouse_keys: MouseKeys) {
 		let editor_mouse_state = EditorMouseState {
 			editor_position: ViewportPosition::new(x, y),
@@ -398,7 +387,6 @@ pub mod test_prelude {
 	pub use graph_craft::document::DocumentNode;
 	pub use graphene_std::raster::{Color, Image};
 	pub use graphene_std::transform::Footprint;
-	pub use graphene_std::{InputAccessor, InputAccessorSource};
 
 	#[macro_export]
 	macro_rules! float_eq {