Add Template operation for basic JSON rendering

src/core/operations/Template.mjs

@@ -0,0 +1,53 @@
+/**
+ * @author kendallgoto [k@kgo.to]
+ * @copyright Crown Copyright 2025
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation.mjs";
+import OperationError from "../errors/OperationError.mjs";
+import Handlebars from "handlebars";
+
+/**
+ * Template operation
+ */
+class Template extends Operation {
+
+    /**
+     * Template constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "Template";
+        this.module = "Handlebars";
+        this.description = "Render a template with Handlebars/Mustache substituting variables using JSON input. Templates will be rendered to plain-text only, to prevent XSS.";
+        this.infoURL = "https://handlebarsjs.com/";
+        this.inputType = "JSON";
+        this.outputType = "string";
+        this.args = [
+            {
+                name: "Template definition (.handlebars)",
+                type: "text",
+                value: ""
+            }
+        ];
+    }
+
+    /**
+     * @param {JSON} input
+     * @param {Object[]} args
+     * @returns {string}
+     */
+    run(input, args) {
+        const [templateStr] = args;
+        try {
+            const template = Handlebars.compile(templateStr);
+            return template(input);
+        } catch (e) {
+            throw new OperationError(e);
+        }
+    }
+}
+
+export default Template;