Follow-me stair light for the Apollo MTR-1 and WLED

ESPHome package for the Apollo MTR-1: tracks people on the stairs with the
LD2450 radar and streams a lit window to a WLED controller over DDP. The
sensor serves a setup wizard that measures the stairs with one walk and
stores the setup on the device.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

wizard/tools/serve.mjs

@@ -0,0 +1,24 @@
+// Serves the wizard folder on the LAN so a phone can open it.
+//   node wizard/tools/serve.mjs [port]
+// Then open http://<this machine>:<port>/ on the phone and enter the sensor's
+// address in the bar that opens (or add ?host=<address>).
+import http from 'node:http';
+import fs from 'node:fs';
+import path from 'node:path';
+import {fileURLToPath} from 'node:url';
+
+const root = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..');
+const port = +(process.argv[2] || 8080);
+const types = {'.html': 'text/html; charset=utf-8', '.js': 'text/javascript', '.mjs': 'text/javascript', '.json': 'application/json',
+  '.css': 'text/css', '.woff2': 'font/woff2', '.txt': 'text/plain; charset=utf-8'};
+
+http.createServer((req, res) => {
+  const p = decodeURIComponent(new URL(req.url, 'http://x').pathname);
+  const f = path.join(root, p === '/' ? 'wizard.html' : p);
+  if (!f.startsWith(root + path.sep)) { res.writeHead(403).end(); return; }
+  fs.readFile(f, (err, data) => {
+    if (err) { res.writeHead(404).end('not found'); return; }
+    res.writeHead(200, {'Content-Type': types[path.extname(f)] || 'application/octet-stream', 'Cache-Control': 'no-store'}).end(data);
+    console.log(new Date().toLocaleTimeString(), req.socket.remoteAddress, p);
+  });
+}).listen(port, '0.0.0.0', () => console.log(`serving ${root} on port ${port}`));