feat: knock notifications for admins + AFK auto-mute in calls

P4-3 — Knock-to-join Notifications for Admins:
- usePendingKnocks() hook reactively tracks knocking members via
  RoomMemberEvent.Membership; returns empty array if user lacks invite power
- Members icon in RoomViewHeader shows a Warning badge with the knock count
  when there are pending requests; badge updates in real time without
  needing to open the drawer; aria-label updated to describe pending count

P5-11 — AFK Auto-Mute in Voice:
- useAfkAutoMute() hook opens a monitoring-only getUserMedia stream,
  connects it to an AnalyserNode, and polls RMS every 500ms
- If mic is on and RMS stays below threshold for the configured timeout,
  calls callEmbed.control.setMicrophone(false) and shows an in-app toast
- Hook is called inside CallControls so monitoring is only active during calls
- Settings: afkAutoMute toggle + afkTimeoutMinutes select (1/5/10/20/30 min,
  default 10) added to Settings → Calls

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/features/room/RoomViewHeader.tsx

@@ -73,6 +73,7 @@ import { useCallEmbed, useCallStart } from '../../hooks/useCallEmbed';
 import { useLivekitSupport } from '../../hooks/useLivekitSupport';
 import { webRTCSupported } from '../../utils/rtc';
 import { MediaGallery } from './MediaGallery';
+import { usePendingKnocks } from '../../hooks/usePendingKnocks';
 
 type RoomMenuProps = {
   room: Room;
@@ -433,6 +434,7 @@ export function RoomViewHeader({ callView }: { callView?: boolean }) {
 
   const [peopleDrawer, setPeopleDrawer] = useSetting(settingsAtom, 'isPeopleDrawer');
   const [galleryOpen, setGalleryOpen] = useState(false);
+  const pendingKnocks = usePendingKnocks(room);
 
   const handleSearchClick = () => {
     const searchParams: _SearchPathSearchParams = {
@@ -682,14 +684,45 @@ export function RoomViewHeader({ callView }: { callView?: boolean }) {
                 }
               >
                 {(triggerRef) => (
-                  <IconButton
-                    fill="None"
-                    ref={triggerRef}
-                    onClick={handleMemberToggle}
-                    aria-label="Toggle member list"
-                  >
-                    <Icon size="400" src={Icons.User} />
-                  </IconButton>
+                  <div style={{ position: 'relative', display: 'inline-flex' }}>
+                    <IconButton
+                      fill="None"
+                      ref={triggerRef}
+                      onClick={handleMemberToggle}
+                      aria-label={
+                        pendingKnocks.length > 0
+                          ? `Toggle member list, ${pendingKnocks.length} pending join request${pendingKnocks.length > 1 ? 's' : ''}`
+                          : 'Toggle member list'
+                      }
+                    >
+                      <Icon size="400" src={Icons.User} />
+                    </IconButton>
+                    {pendingKnocks.length > 0 && (
+                      <Badge
+                        aria-hidden
+                        variant="Warning"
+                        fill="Solid"
+                        radii="Pill"
+                        size="200"
+                        style={{
+                          position: 'absolute',
+                          top: '-2px',
+                          right: '-2px',
+                          pointerEvents: 'none',
+                          fontSize: '9px',
+                          minWidth: '14px',
+                          height: '14px',
+                          padding: '0 3px',
+                          display: 'flex',
+                          alignItems: 'center',
+                          justifyContent: 'center',
+                          lineHeight: 1,
+                        }}
+                      >
+                        {pendingKnocks.length > 9 ? '9+' : pendingKnocks.length}
+                      </Badge>
+                    )}
+                  </div>
                 )}
               </TooltipProvider>
             )}