[client] Sweep connections on network loss via a shared netevents manager

Losing the last network only flipped the availability state: the dead
management, signal and relay sockets stayed silently connected until their
own timeouts, so the client kept reporting Connected with no network at all.

Introduce client/netevents with a Manager that ties the availability state,
the connection sweeper and the status recorder together, and move the
netstate and netsweep packages under it (netsweep renamed to sweep).
SetNetworkAvailable(false) now also sweeps the registered connections so
their owners redial and the listener reaches the NoNetwork state.

The Android and iOS bindings own a Manager instance and inject it through
the constructors; consumers hold the concrete *Manager whose nil zero value
reports always-online and never sweeps, with interfaces kept only as
parameter contracts. The relay guard settle wait moved into the Manager as
WaitSettled, removing the netevents import from the relay package.

client/android/client.go

@@ -26,8 +26,7 @@ import (
 	"github.com/netbirdio/netbird/client/internal/routemanager"
 	"github.com/netbirdio/netbird/client/internal/stdnet"
 	"github.com/netbirdio/netbird/client/net"
-	"github.com/netbirdio/netbird/client/netstate"
-	"github.com/netbirdio/netbird/client/netsweep"
+	"github.com/netbirdio/netbird/client/netevents"
 	"github.com/netbirdio/netbird/client/system"
 	"github.com/netbirdio/netbird/formatter"
 	"github.com/netbirdio/netbird/route"
@@ -82,13 +81,10 @@ type Client struct {
 	deviceName            string
 	uiVersion             string
 	networkChangeListener listener.NetworkChangeListener
-	// netState outlives engine restarts: it mirrors the OS connectivity, not
-	// the engine lifecycle. Run and RunWithoutLogin inject it into each new
-	// ConnectClient, which distributes it to every reconnection loop.
-	netState *netstate.State
-
-	// sweeper also outlives engine restarts; NotifyNetworkChange sweeps it.
-	sweeper *netsweep.Sweeper
+	// netMgr outlives engine restarts: it mirrors the OS connectivity, not
+	// the engine lifecycle. Run and RunWithoutLogin inject its state and
+	// sweeper into each new ConnectClient.
+	netMgr *netevents.Manager
 
 	stateMu       sync.RWMutex
 	connectClient *internal.ConnectClient
@@ -153,16 +149,16 @@ func NewClient(androidSDKVersion int, deviceName string, uiVersion string, tunAd
 
 	net.SetAndroidProtectSocketFn(tunAdapter.ProtectSocket)
 	system.SetIFaceDiscover(iFaceDiscover)
+	recorder := peer.NewRecorder("")
 	return &Client{
 		deviceName:            deviceName,
 		uiVersion:             uiVersion,
 		tunAdapter:            tunAdapter,
 		iFaceDiscover:         iFaceDiscover,
-		recorder:              peer.NewRecorder(""),
+		recorder:              recorder,
 		ctxCancelLock:         &sync.Mutex{},
 		networkChangeListener: networkChangeListener,
-		netState:              netstate.New(),
-		sweeper:               netsweep.New(),
+		netMgr:                netevents.NewManager(recorder),
 	}
 }
 
@@ -203,8 +199,9 @@ func (c *Client) Run(platformFiles PlatformFiles, urlOpener URLOpener, isAndroid
 	}
 	// todo do not throw error in case of cancelled context
 	ctx = internal.CtxInitState(ctx)
+
 	connectClient := internal.NewConnectClient(ctx, cfg, c.recorder,
-		internal.WithNetworkState(c.netState), internal.WithSweeper(c.sweeper))
+		internal.WithNetEvents(c.netMgr))
 	c.setState(cfg, cacheDir, cfgFile, connectClient)
 	// This path runs the interactive SSO flow, so reaching here means the peer
 	// is authenticated again — release the latch Status() reports from. Clear
@@ -246,7 +243,7 @@ func (c *Client) RunWithoutLogin(platformFiles PlatformFiles, dns *DNSList, dnsR
 	// todo do not throw error in case of cancelled context
 	ctx = internal.CtxInitState(ctx)
 	connectClient := internal.NewConnectClient(ctx, cfg, c.recorder,
-		internal.WithNetworkState(c.netState), internal.WithSweeper(c.sweeper))
+		internal.WithNetEvents(c.netMgr))
 	c.setState(cfg, cacheDir, cfgFile, connectClient)
 	return connectClient.RunOnAndroid(c.tunAdapter, c.iFaceDiscover, c.networkChangeListener, slices.Clone(dns.items), dnsReadyListener, stateFile, cacheDir)
 }
@@ -298,9 +295,12 @@ func (c *Client) GetTunSettings() (*TunSettings, error) {
 // While unavailable, the internal reconnect loops suspend their attempts and
 // the connection listener reports NoNetwork instead of Connecting; when
 // availability returns, the loops resume immediately with a fresh backoff.
+// Losing the last network also sweeps the registered connections: nothing can
+// redial while offline, so the stale sockets would otherwise stay silently
+// "connected" until their own timeouts and the client would keep reporting
+// Connected with no network at all.
 func (c *Client) SetNetworkAvailable(available bool) {
-	c.netState.Set(available)
-	c.recorder.SetNetworkAvailable(available)
+	c.netMgr.SetNetworkAvailable(available)
 }
 
 // NotifyNetworkChange marks the management, signal and relay connections
@@ -308,8 +308,7 @@ func (c *Client) SetNetworkAvailable(available bool) {
 // whatever has not redialed on the new network by then. The engine and the
 // TUN device stay untouched.
 func (c *Client) NotifyNetworkChange() {
-	c.sweeper.MarkNetworkChange()
-	log.Infof("network change: connections marked stale")
+	c.netMgr.NotifyNetworkChange()
 }
 
 // DebugBundle generates a debug bundle, uploads it, and returns the upload key.