refactor: adopt POSITIONS constants, fix ESLint warnings, break menuUtils into modules

- Replace hardcoded position strings with POSITIONS.* constants
- Prefix unused variables with _ to resolve no-unused-vars warnings
- Fix no-prototype-builtins with Object.prototype.hasOwnProperty.call()
- Extract menuUtils.js (543 lines) into 6 focused modules under menu/
- menuUtils.js now 35 lines, delegates via prototype mixin pattern
- Add 158 unit tests for ConfigManager, MeasurementContainer, ValidationUtils

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

src/helper/menu/htmlGeneration.js

@@ -0,0 +1,73 @@
+/**
+ * HTML generation and endpoint methods for MenuUtils.
+ * Handles generating dropdown HTML and serving MenuUtils code to the browser.
+ */
+
+const htmlGeneration = {
+  generateHtml(htmlElement, options, savedValue) {
+    htmlElement.innerHTML = options.length
+      ? `<option value="">Select...</option>${options
+          .map((opt) => `<option value="${opt}">${opt}</option>`)
+          .join("")}`
+      : "<option value=''>No options available</option>";
+
+    if (savedValue && options.includes(savedValue)) {
+      htmlElement.value = savedValue;
+    }
+  },
+
+  createMenuUtilsEndpoint(RED, nodeName, customHelpers = {}) {
+      RED.httpAdmin.get(`/${nodeName}/resources/menuUtils.js`, function(req, res) {
+        console.log(`Serving menuUtils.js for ${nodeName} node`);
+        res.set('Content-Type', 'application/javascript');
+
+        const browserCode = this.generateMenuUtilsCode(nodeName, customHelpers);
+        res.send(browserCode);
+      }.bind(this));
+    },
+
+  generateMenuUtilsCode(nodeName, customHelpers = {}) {
+    const defaultHelpers = {
+      validateRequired: `function(value) {
+        return value && value.toString().trim() !== '';
+      }`,
+      formatDisplayValue: `function(value, unit) {
+        return \`\${value} \${unit || ''}\`.trim();
+      }`
+    };
+
+    const allHelpers = { ...defaultHelpers, ...customHelpers };
+
+    const helpersCode = Object.entries(allHelpers)
+      .map(([name, func]) => `        ${name}: ${func}`)
+      .join(',\n');
+
+    const classCode = this.constructor.toString(); // <-- this gives full class MenuUtils {...}
+
+    return `
+      // Create EVOLV namespace structure
+      window.EVOLV = window.EVOLV || {};
+      window.EVOLV.nodes = window.EVOLV.nodes || {};
+      window.EVOLV.nodes.${nodeName} = window.EVOLV.nodes.${nodeName} || {};
+
+      // Inject MenuUtils class
+      ${classCode}
+
+      // Expose MenuUtils instance to namespace
+      window.EVOLV.nodes.${nodeName}.utils = {
+        menuUtils: new MenuUtils(),
+
+        helpers: {
+  ${helpersCode}
+        }
+      };
+
+      // Optionally expose globally
+      window.MenuUtils = MenuUtils;
+
+      console.log('${nodeName} utilities loaded in namespace');
+    `;
+  },
+};
+
+module.exports = htmlGeneration;