[client] Extract peerRoutesAddr helper in toExcludedLazyPeers

Pure stylistic refactor: pull the AllowedIPs match into a named
peerRoutesAddr helper and document why forward-target peers are excluded
from lazy connections. No behavior change; the existing address match is
preserved as-is.

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

client/internal/engine.go

@@ -2561,13 +2561,13 @@ func (e *Engine) updateForwardRules(rules []*mgmProto.ForwardingRule) ([]firewal
 
 func (e *Engine) toExcludedLazyPeers(rules []firewallManager.ForwardRule, peers []*mgmProto.RemotePeerConfig) map[string]bool {
 	excludedPeers := make(map[string]bool)
+
+	// Ingress forward targets: inbound forwarded traffic is initiated remotely and
+	// cannot wake a lazy connection, so the peer routing the target must stay
+	// permanently connected.
 	for _, r := range rules {
-		ip := r.TranslatedAddress
 		for _, p := range peers {
-			for _, allowedIP := range p.GetAllowedIps() {
-				if allowedIP != ip.String() {
-					continue
-				}
+			if peerRoutesAddr(p, r.TranslatedAddress) {
 				log.Infof("exclude forwarder peer from lazy connection: %s", p.GetWgPubKey())
 				excludedPeers[p.GetWgPubKey()] = true
 			}
@@ -2577,6 +2577,16 @@ func (e *Engine) toExcludedLazyPeers(rules []firewallManager.ForwardRule, peers
 	return excludedPeers
 }
 
+// peerRoutesAddr verifies if the peer is a router for a given address.
+func peerRoutesAddr(p *mgmProto.RemotePeerConfig, addr netip.Addr) bool {
+	for _, allowedIP := range p.GetAllowedIps() {
+		if allowedIP == addr.String() {
+			return true
+		}
+	}
+	return false
+}
+
 // isChecksEqual checks if two slices of checks are equal.
 func isChecksEqual(checks1, checks2 []*mgmProto.Checks) bool {
 	normalize := func(checks []*mgmProto.Checks) []string {