refactor(measurement): modularize editor JS

Move inline <script> from measurement.html into 8 modules under
src/editor/. measurement.js adds the static-file routes that serve them
to Node-RED.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

measurement.js

@@ -1,4 +1,5 @@
 const nameOfNode = 'measurement'; // this is the name of the node, it should match the file name and the node type in Node-RED
+const path = require('path');
 const nodeClass = require('./src/nodeClass.js'); // this is the specific node class
 const { MenuManager, configManager, assetApiConfig } = require('generalFunctions');
 const assetUtils = require('generalFunctions/assetUtils');
@@ -38,6 +39,18 @@ module.exports = function(RED) {
     }
   });
 
+  // Editor JS modules — loaded by measurement.html via <script src=...> tags.
+  // Files live in src/editor/. Filename is restricted to a safe charset to
+  // prevent path-traversal. Mirror of the pumpingStation pattern.
+  RED.httpAdmin.get(`/${nameOfNode}/editor/:file`, (req, res) => {
+    const safe = String(req.params.file || '').replace(/[^a-zA-Z0-9._-]/g, '');
+    if (!safe.endsWith('.js')) return res.status(400).send('// invalid');
+    res.type('application/javascript');
+    res.sendFile(path.join(__dirname, 'src', 'editor', safe), (err) => {
+      if (err && !res.headersSent) res.status(404).send('// editor module not found');
+    });
+  });
+
   RED.httpAdmin.post(`/${nameOfNode}/asset-reg`, async (req, res) => {
     const body = req.body || {};
     const assetPayload = body.asset;