Fix atlas-card click + wire live audio + verify pipeline

- Add hidden admin-screen stub to index.html. The live JS calls
  adminEl.setAttribute() on every hashchange (via openAdmin/closeAdmin);
  with the element missing those threw a null-ref that killed
  syncRouter mid-flight, so atlas card clicks set the hash but never
  opened the detail modal. Stub is empty - menu items navigate to
  BirdNET-Pi's stock pages instead of triggering in-app admin.

- Point the live-audio Audio() at /stream (BirdNET-Pi's existing
  icecast reverse-proxy from install_services.sh:189) instead of the
  worker's /birdnet/stream. The drawer's live-audio button now plays
  real BirdNET-Pi audio on local installs.

Verified end-to-end in Docker container:
- Landing collage: 4 tiles render from seeded DB
- Atlas click: detail modal opens with image + sci/common name
- Menu drawer: opens, shows 4 items (no password in local mode)
- Auto-refresh: INSERTed Bubo virginianus into birds.db, forced
  refresh via window picker re-click, tile count 4→5 with the new
  species appearing in the collage.

avian/frontend/apt.js

@@ -1322,7 +1322,7 @@
       // race a timeout because icecast can take 1–10s to warm up
       // depending on tunnel + bitrate.
       return new Promise(function (resolve, reject) {
-        liveEl = new Audio('?t=' + Date.now());
+        liveEl = new Audio('/stream?t=' + Date.now());
         // No crossOrigin — the stream is same-origin via the worker
         // and crossOrigin='anonymous' would require CORS headers
         // icecast doesn't send.

avian/frontend/index.html

@@ -187,6 +187,18 @@
   <button type="button" data-i="2">atlas</button>
 </nav>
 
+
+<!-- AvianVisitors: empty admin-screen stub. The live JS expects this
+     element to exist (openAdmin/closeAdmin call setAttribute on it).
+     Menu items navigate to BirdNET-Pi's stock pages instead of opening
+     in-app admin views, so this stays empty. -->
+<section class="admin-screen" id="adminScreen" aria-hidden="true">
+  <div class="admin-frame">
+    <header class="admin-title"><h1 id="adminTitle"></h1></header>
+    <div class="admin-body" id="adminBody"></div>
+  </div>
+</section>
+
 <script src="./apt.js"></script>
 </body>
 </html>