fix(call): ringtone loudness, caller decline notice, All-Muted badge

Three issues from live testing:
- A1: the 'classic' ringtone (call.ogg, mastered near full scale) was much
  louder than the synthesized styles. Attenuate it (CLASSIC_GAIN 0.45) so all
  ringtones sit at a comparable level.
- A3/A4: the caller had no indication when a DM/group callee declined — their
  UI kept "ringing" until the notification lifetime expired. IncomingCallListener
  now listens for RTCDecline events for a call we're hosting in the room and
  toasts the caller ("<name> declined your call").
- G1: the PiP "All muted" badge fired when any single remote participant muted.
  useRemoteAllMuted now returns true only when there is >=1 remote and every
  remote participant is muted.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/components/CallEmbedProvider.tsx

@@ -37,6 +37,7 @@ import {
   useCallStart,
 } from '../hooks/useCallEmbed';
 import { callChatAtom, callEmbedAtom } from '../state/callEmbed';
+import { toastQueueAtom } from '../state/toast';
 import { CallEmbed, useCallControlState } from '../plugins/call';
 import { useSelectedRoom } from '../hooks/router/useSelectedRoom';
 import { ScreenSize, useScreenSizeContext } from '../hooks/useScreenSize';
@@ -405,6 +406,7 @@ function IncomingCallListener({ callEmbed, joined }: IncomingCallListenerProps)
   const mx = useMatrixClient();
   const directs = useAtomValue(mDirectAtom);
   const { navigateRoom } = useRoomNavigate();
+  const setToast = useSetAtom(toastQueueAtom);
 
   const [callInfo, setCallInfo] = useState<IncomingCallInfo>();
   const dm = callInfo ? directs.has(callInfo.room.roomId) : false;
@@ -424,6 +426,31 @@ function IncomingCallListener({ callEmbed, joined }: IncomingCallListenerProps)
         await event.getDecryptionPromise();
       }
 
+      // Caller-side: a participant declined a call we're hosting in this room.
+      // Without this the caller's UI keeps "ringing" until the notification
+      // lifetime expires, with no indication the callee said no.
+      if (event.getType() === EventType.RTCDecline) {
+        const decliner = event.getSender();
+        if (
+          data.liveEvent &&
+          room &&
+          decliner &&
+          decliner !== mx.getSafeUserId() &&
+          callEmbed?.roomId === room.roomId
+        ) {
+          const declinerName =
+            getMemberDisplayName(room, decliner) ?? getMxIdLocalPart(decliner) ?? decliner;
+          setToast({
+            id: `rtc-decline-${event.getId() ?? decliner}`,
+            displayName: declinerName,
+            body: 'Declined your call',
+            roomName: room.name,
+            roomId: room.roomId,
+          });
+        }
+        return;
+      }
+
       if (
         !room ||
         event.getType() !== EventType.RTCNotification ||
@@ -486,7 +513,7 @@ function IncomingCallListener({ callEmbed, joined }: IncomingCallListenerProps)
 
       setCallInfo(info);
     },
-    [mx, directs],
+    [mx, directs, callEmbed, setToast],
   );
 
   useEffect(() => {