Move session state out of the network interface caches and replace the selection hijacks with explicit parameters (#4379)

* Move drag offsets out of the stack dependents cache into dedicated drag session state

* Replace the move_layer_to_stack selection hijack with a seeded stack dependents load

* Move text measurement into a neutral utility module out of the overlays layer

* Deduplicate the document bounds queries and name the artboard clip input index

* Replace the remove_references_from_network selection hijack with an explicit shift set

* Extract shared import and export wire disconnection used by the expose handlers

* Extract the shared epilogue of the import and export removal operations

* Move the post node lookup into the network interface to fix the layering inversion

* Clear drag offsets when the stack dependents cache unloads so programmatic shifts cannot replay them

* Use the thread-local text context for text measurement instead of a process-global mutex

* Resolve the post node lookup within the network being edited instead of the document root

editor/src/test_utils.rs

@@ -324,11 +324,19 @@ impl EditorTestUtils {
 	}
 
 	pub async fn create_node_by_name(&mut self, node_type: DefinitionIdentifier) -> NodeId {
+		self.create_node(node_type, None).await
+	}
+
+	pub async fn create_node_by_name_at(&mut self, node_type: DefinitionIdentifier, x: i32, y: i32) -> NodeId {
+		self.create_node(node_type, Some((x, y))).await
+	}
+
+	async fn create_node(&mut self, node_type: DefinitionIdentifier, xy: Option<(i32, i32)>) -> NodeId {
 		let node_id = NodeId::new();
 		self.handle_message(NodeGraphMessage::CreateNodeFromContextMenu {
 			node_id: Some(node_id),
 			node_type,
-			xy: None,
+			xy,
 			add_transaction: true,
 		})
 		.await;