fix: WebRTC call bugs and add Call Settings screen

Bug fixes:
- Fix invitePeer() bypassing CallManager state tracking, causing
  invited peers to not appear in pendingPeerPubKeys
- Remove 10-minute proximity wake lock timeout so it lasts the
  full call duration (released on cleanup)
- Send hangup to peers on caller timeout so callees stop ringing
  immediately instead of waiting for their own 60s timeout
- Remove duplicate cleanup() call on Ended→Idle transition

New feature:
- Add Call Settings screen (TURN servers + video quality)
- Users can configure custom TURN servers for restrictive networks
- Default STUN/TURN servers are always active and displayed
- Video resolution options: 480p, 720p (default), 1080p
- Configurable max video bitrate: 750kbps, 1.5Mbps, 3Mbps
- Settings wired into IceServerConfig and CallMediaManager

https://claude.ai/code/session_01F5RF2yzngiMr1v2gr7f1GP

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/call/CallManager.kt

@@ -765,22 +765,32 @@ class CallManager(
         timeoutJob =
             scope.launch {
                 delay(CALL_TIMEOUT_MS)
-                val current = _state.value
-                val currentCallId =
-                    when (current) {
-                        is CallState.Offering -> current.callId
-                        is CallState.IncomingCall -> current.callId
-                        else -> null
-                    }
-                if (currentCallId == callId) {
-                    val peerPubKeys =
+                val peerPubKeys: Set<HexKey>
+                val wasOffering: Boolean
+                stateMutex.withLock {
+                    val current = _state.value
+                    val currentCallId =
+                        when (current) {
+                            is CallState.Offering -> current.callId
+                            is CallState.IncomingCall -> current.callId
+                            else -> null
+                        }
+                    if (currentCallId != callId) return@launch
+                    peerPubKeys =
                         when (current) {
                             is CallState.Offering -> current.peerPubKeys
                             is CallState.IncomingCall -> current.peerPubKeys()
                             else -> return@launch
                         }
+                    wasOffering = current is CallState.Offering
                     transitionToEnded(callId, peerPubKeys, EndReason.TIMEOUT)
                 }
+                // Notify peers so their phones stop ringing immediately
+                // instead of waiting for their own 60-second timeout.
+                if (wasOffering && peerPubKeys.isNotEmpty()) {
+                    val result = factory.createGroupHangup(peerPubKeys, callId, signer = signer)
+                    result.wraps.forEach { publishEvent(it) }
+                }
             }
     }