Show peer availability with stale markers and add Sharing settings

frontend/index.html

@@ -221,6 +221,7 @@
               <div class="np-text">
                 <div class="np-title" id="npTitle"></div>
                 <div class="np-channel" id="npChannel"></div>
+                <div class="np-avail hidden" id="npAvail" aria-live="polite"></div>
               </div>
               <div class="np-actions">
                 <button id="queueBtn" class="np-btn" title="Add to the temporary queue">＋ Queue</button>
@@ -564,6 +565,7 @@
     <script src="sha256.js"></script>
     <script src="device-db.js"></script>
     <script src="p2p-client.js"></script>
+    <script src="p2p-core.js"></script>
     <script src="async-guard.js"></script>
     <script src="sw-update.js"></script>
     <script src="app.js"></script>