[ios] Ensure route settlement on iOS before handling DNS responses (#5360)

* Ensure route settlement on iOS before handling DNS responses to prevent bypassing the tunnel.

* add more logs

* rollback debug changes

* rollback  changes

* [client] Improve logging and add comments for iOS route settlement logic

- Switch iOS route settlement log level from Debug to Trace for finer control.
- Add clarifying comments for `waitForRouteSettlement` on non-iOS platforms.

---------

Co-authored-by: mlsmaycon <mlsmaycon@gmail.com>

client/internal/routemanager/dnsinterceptor/handler_ios.go

@@ -0,0 +1,20 @@
+//go:build ios
+
+package dnsinterceptor
+
+import (
+	"time"
+
+	log "github.com/sirupsen/logrus"
+)
+
+const routeSettleDelay = 500 * time.Millisecond
+
+// waitForRouteSettlement introduces a short delay on iOS to allow
+// setTunnelNetworkSettings to apply route changes before the DNS
+// response reaches the application. Without this, the first request
+// to a newly resolved domain may bypass the tunnel.
+func waitForRouteSettlement(logger *log.Entry) {
+	logger.Tracef("waiting %v for iOS route settlement", routeSettleDelay)
+	time.Sleep(routeSettleDelay)
+}