Nodes: use relative references inside examples/jsm (#27381)

Fixes https://github.com/mrdoob/three.js/issues/27354

examples/jsm/loaders/MaterialXLoader.js

@@ -19,7 +19,7 @@ import {
 	mx_safepower, mx_contrast,
 	mx_srgb_texture_to_lin_rec709,
 	saturation
-} from 'three/nodes';
+} from '../nodes/Nodes.js';
 
 const colorSpaceLib = {
 	mx_srgb_texture_to_lin_rec709

examples/jsm/renderers/webgl-legacy/nodes/SlotNode.js

@@ -1,4 +1,4 @@
-import { Node } from 'three/nodes';
+import { Node } from '../../../nodes/Nodes.js';
 
 class SlotNode extends Node {
 

examples/jsm/renderers/webgl-legacy/nodes/WebGLNodeBuilder.js

@@ -1,4 +1,4 @@
-import { defaultShaderStages, NodeFrame, MathNode, GLSLNodeParser, NodeBuilder, normalView } from 'three/nodes';
+import { defaultShaderStages, NodeFrame, MathNode, GLSLNodeParser, NodeBuilder, normalView } from '../../../nodes/Nodes.js';
 import SlotNode from './SlotNode.js';
 import { PerspectiveCamera, ShaderChunk, ShaderLib, UniformsUtils, UniformsLib } from 'three';
 

examples/jsm/renderers/webgl-legacy/nodes/WebGLNodes.js

@@ -1,5 +1,5 @@
 import { WebGLNodeBuilder } from './WebGLNodeBuilder.js';
-import { NodeFrame } from 'three/nodes';
+import { NodeFrame } from '../../../nodes/Nodes.js';
 
 import { Material } from 'three';