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>

firmware/follow-me-button.js

@@ -0,0 +1,29 @@
+// Adds a "Set up Follow-Me" link to ESPHome's stock web page, opening the
+// setup wizard the device serves at /followme. Loaded by the stock page as
+// /0.js (web_server js_include in follow-me.yaml).
+(() => {
+  const ID = 'followme-setup-link';
+  const add = () => {
+    if (document.getElementById(ID)) return;
+    const a = document.createElement('a');
+    a.id = ID;
+    a.href = '/followme';
+    a.textContent = 'Set up Follow-Me';
+    a.style.cssText = [
+      'position:fixed',
+      'right:20px',
+      'bottom:20px',
+      'z-index:9999',
+      'padding:10px 16px',
+      'background:#0e0e10',
+      'color:#ece8df',
+      'border:1px solid rgba(236,232,223,.35)',
+      'border-radius:3px',
+      "font:500 14px/1.2 'IBM Plex Sans',system-ui,sans-serif",
+      'text-decoration:none',
+    ].join(';');
+    document.body.appendChild(a);
+  };
+  if (document.readyState === 'loading') document.addEventListener('DOMContentLoaded', add);
+  else add();
+})();