Add PreviewToLoad node for bridging preview images to LoadImage nodes

Previews an image (like PreviewImage) and saves a copy to input/ so a
LoadImage node can reference it.  JS extension adds a target-node-ID
widget and "Send to Load Image" button that updates the target's combo.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

web/image_preview.js

@@ -0,0 +1,68 @@
+import { app } from "../../scripts/app.js";
+
+app.registerExtension({
+    name: "jdl.preview.to.load",
+
+    async beforeRegisterNodeDef(nodeType, nodeData, app) {
+        if (nodeData.name !== "JDL_PreviewToLoad") return;
+
+        const origOnNodeCreated = nodeType.prototype.onNodeCreated;
+        nodeType.prototype.onNodeCreated = function () {
+            origOnNodeCreated?.apply(this, arguments);
+
+            this.addWidget("number", "load_image_node_id", 0, (v) => {}, {
+                min: 0,
+                max: 99999,
+                step: 10,
+                precision: 0,
+            });
+
+            this.addWidget("button", "Send to Load Image", null, () => {
+                const nodeIdWidget = this.widgets?.find(w => w.name === "load_image_node_id");
+                if (!nodeIdWidget) return;
+
+                const targetId = Math.round(nodeIdWidget.value);
+                const targetNode = app.graph.getNodeById(targetId);
+                if (!targetNode) {
+                    console.warn("[PreviewToLoad] No node found with ID:", targetId);
+                    return;
+                }
+
+                const filename = this.last_input_filename;
+                if (!filename) {
+                    console.warn("[PreviewToLoad] No filename available. Run the workflow first.");
+                    return;
+                }
+
+                const imageWidget = targetNode.widgets?.find(w => w.name === "image");
+                if (!imageWidget) {
+                    console.warn("[PreviewToLoad] Target node has no 'image' widget.");
+                    return;
+                }
+
+                // Add filename to combo options if not already present
+                if (imageWidget.options?.values && !imageWidget.options.values.includes(filename)) {
+                    imageWidget.options.values.push(filename);
+                }
+
+                imageWidget.value = filename;
+                if (imageWidget.callback) {
+                    imageWidget.callback(filename);
+                }
+
+                app.graph.setDirtyCanvas(true, true);
+            });
+
+            this.setSize(this.computeSize());
+        };
+
+        const origOnExecuted = nodeType.prototype.onExecuted;
+        nodeType.prototype.onExecuted = function (output) {
+            origOnExecuted?.apply(this, arguments);
+
+            if (output?.input_filename?.length) {
+                this.last_input_filename = output.input_filename[0];
+            }
+        };
+    },
+});