dashboard: browser notifications for operator-bound events

three signals fire OS notifications:
- new approval lands in the queue (per id, via /api/state delta)
- new ask_operator question queued (per id)
- broker message sent to operator (live via SSE)

first /api/state render after page load seeds the 'seen' sets
without firing — only items that arrive while the page is open
count. controls in a row under the banner: 🔔 enable
notifications (calls requestPermission, hides on grant), 🔕 mute /
🔔 unmute toggle (localStorage-backed so operator can silence
without revoking the permission), inline status text when blocked
or unsupported.

notification tag='hyperhive' collapses rapid bursts; onclick
focuses the dashboard tab. requires secure context (HTTPS or
localhost) — on other origins the API is unavailable and the
controls hide themselves.

todo: entry dropped.

hive-c0re/assets/index.html

@@ -10,6 +10,13 @@
 ░▒▓█▓▒░  HYPERHIVE  ░▒▓█▓▒░  HIVE-C0RE  ░▒▓█▓▒░  WE ARE THE WIRED  ░▒▓█▓▒░
   </pre>
 
+  <div id="notif-row" class="notif-row">
+    <button type="button" id="notif-enable" class="btn btn-notif" hidden>🔔 enable notifications</button>
+    <button type="button" id="notif-mute"   class="btn btn-notif" hidden>🔕 mute</button>
+    <button type="button" id="notif-unmute" class="btn btn-notif" hidden>🔔 unmute</button>
+    <span id="notif-status" class="meta" hidden></span>
+  </div>
+
   <h2>◆ C0NTAINERS ◆</h2>
   <div class="divider">══════════════════════════════════════════════════════════════</div>
   <div id="containers-section">