peer/status: move relay-state reads off the main mux

GetRelayStates held d.mux (RLock) while calling into the relay
Manager (RelayStates/RelayConnectError/ServerURLs). Those calls can be
slow or block on the relay manager's own locks while it is reconnecting,
which kept the central Status mutex held and stalled every peer state
writer (UpdatePeerState, ReplaceOfflinePeers, etc.) contending for it.

Guard relayMgr/relayStates with a dedicated muxRelays mutex and release
it before invoking the relay Manager, so the relay read path no longer
contends with the hot peer-state writers on d.mux.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

client/internal/peer/status.go

@@ -192,6 +192,7 @@ func (s *StatusChangeSubscription) Events() chan map[string]RouterState {
 // Pure read methods take RLock; anything that mutates state takes Lock.
 type Status struct {
 	mux                   sync.RWMutex
+	muxRelays             sync.RWMutex
 	peers                 map[string]State
 	ipToKey               map[string]string
 	changeNotify          map[string]map[string]*StatusChangeSubscription // map[peerID]map[subscriptionID]*StatusChangeSubscription
@@ -244,8 +245,8 @@ func NewRecorder(mgmAddress string) *Status {
 }
 
 func (d *Status) SetRelayMgr(manager *relayClient.Manager) {
-	d.mux.Lock()
+	d.muxRelays.Lock()
-	defer d.mux.Unlock()
+	defer d.muxRelays.Unlock()
 	d.relayMgr = manager
 }
 
@@ -906,8 +907,8 @@ func (d *Status) MarkSignalConnected() {
 }
 
 func (d *Status) UpdateRelayStates(relayResults []relay.ProbeResult) {
-	d.mux.Lock()
+	d.muxRelays.Lock()
-	defer d.mux.Unlock()
+	defer d.muxRelays.Unlock()
 	d.relayStates = relayResults
 }
 
@@ -1018,24 +1019,26 @@ func (d *Status) GetSignalState() SignalState {
 
 // GetRelayStates returns the stun/turn/permanent relay states
 func (d *Status) GetRelayStates() []relay.ProbeResult {
-	d.mux.RLock()
+	d.muxRelays.RLock()
-	defer d.mux.RUnlock()
 	if d.relayMgr == nil {
+		defer d.muxRelays.RUnlock()
 		return d.relayStates
 	}
 
+	relayMgr := d.relayMgr
 	// extend the list of stun, turn servers with the relay server connections
 	relayStates := slices.Clone(d.relayStates)
+	d.muxRelays.RUnlock()
 
-	states := d.relayMgr.RelayStates()
+	states := relayMgr.RelayStates()
 	if len(states) == 0 {
 		// no relay connection tracked yet; surface configured servers as
 		// unavailable with the real reconnect error when known
 		err := relayClient.ErrRelayClientNotConnected
-		if connErr := d.relayMgr.RelayConnectError(); connErr != nil {
+		if connErr := relayMgr.RelayConnectError(); connErr != nil {
 			err = connErr
 		}
-		for _, r := range d.relayMgr.ServerURLs() {
+		for _, r := range relayMgr.ServerURLs() {
 			relayStates = append(relayStates, relay.ProbeResult{
 				URI: r,
 				Err: err,