feat: sign out all operator sessions (#287)

frontend/index.html

@@ -14,6 +14,7 @@ html, body { height: 100%; margin: 0; background: var(--bg); color: var(--text);
 header { position: sticky; top: 0; z-index: 20; padding: 12px 16px; display:flex; gap:16px; align-items:center; justify-content:space-between; background: linear-gradient(180deg, rgba(11,21,38,.95), rgba(11,21,38,.55), transparent); backdrop-filter: blur(4px); border-bottom: 1px solid #1b2d45; }
 .toolbar { display:flex; gap:10px; align-items:center; flex-wrap:wrap; }
 button { background: linear-gradient(180deg,#1f3a5f,#15324d); border:1px solid #2a496e; color:#e5e7eb; padding:8px 12px; border-radius:10px; cursor:pointer; }
+#sign-out-all { min-height:44px; }
 button:hover { filter: brightness(1.15); }
 .panel { border: 1px solid #1b2d45; border-radius: 14px; padding: 12px; background: rgba(11,21,38,.92); }
 .panel > summary { cursor: pointer; list-style-position: inside; }
@@ -298,6 +299,7 @@ textarea { resize: vertical; min-height: 120px; }
     <div class="status"><span class="dot"></span><span class="small" id="status">Live</span></div>
     <button id="refresh">Refresh</button>
     <button id="sign-out" type="button">Sign out &amp; clear this device</button>
+    <button id="sign-out-all" type="button">Sign out all devices</button>
     <button id="open-palette">Command</button>
     <span class="small muted" id="clock"></span>
   </div>