fix(route): handle synthetic load balancer routes consistently

Synthetic load balancer routes were created with SchemeNone and a zero
proxy port, so the embedded Route logic treated them as excluded routes.
That caused them to be keyed like excluded routes instead of by alias,
which broke HTTP route lookup in reverse proxy load balancer tests.

Override Key and ShouldExclude for synthetic load balancer routes so
they stay addressable through the HTTP route pool while preserving the
existing behavior for normal backend routes.

Also guard addToLoadBalancer against a nil Homepage on an existing
linked route, and update the reverse proxy test to use the in-memory
test entrypoint rather than depending on real listener setup.

internal/route/reverse_proxy.go

@@ -123,6 +123,24 @@ func (r *ReverseProxyRoute) ReverseProxy() *reverseproxy.ReverseProxy {
 	return r.rp
 }
 
+func (r *ReverseProxyRoute) isSyntheticLoadBalancerRoute() bool {
+	return r.loadBalancer != nil && r.rp == nil
+}
+
+func (r *ReverseProxyRoute) Key() string {
+	if r.isSyntheticLoadBalancerRoute() {
+		return r.Alias
+	}
+	return r.Route.Key()
+}
+
+func (r *ReverseProxyRoute) ShouldExclude() bool {
+	if r.isSyntheticLoadBalancerRoute() {
+		return false
+	}
+	return r.Route.ShouldExclude()
+}
+
 // Start implements task.TaskStarter.
 func (r *ReverseProxyRoute) Start(parent task.Parent) error {
 	r.task = parent.Subtask("http."+r.Name(), false)
@@ -206,7 +224,7 @@ func (r *ReverseProxyRoute) addToLoadBalancer(parent task.Parent, ep entrypoint.
 		linked = l.(*ReverseProxyRoute) // it must be a reverse proxy route
 		lb = linked.loadBalancer
 		lb.UpdateConfigIfNeeded(cfg)
-		if linked.Homepage.Name == "" {
+		if linked.Homepage == nil || linked.Homepage.Name == "" {
 			linked.Homepage = r.Homepage
 		}
 	} else {