Require access to Still via method

This commit adds a safeguard to accessing the still from a specific
component by requiring access via the component.GetStill method.

internal/dis/component/server/list/api.go

@@ -41,7 +41,7 @@ type APISystem struct {
 
 func (a *API) HandleRoute(ctx context.Context, path string) (http.Handler, error) {
 	return &api.Handler[[]APISystem]{
-		Config: a.Config,
+		Config: component.GetStill(a).Config,
 		Auth:   a.dependencies.Auth,
 
 		Methods: []string{"GET"},

internal/dis/component/server/list/list.go

@@ -35,8 +35,9 @@ func (li *ListInstances) Infos() []status.WissKI {
 
 // ShouldShowList determines if a list should be shown for the given request
 func (li *ListInstances) ShouldShowList(r *http.Request) bool {
-	allowPrivate := li.Config.Home.List.Private.Value
-	allowPublic := li.Config.Home.List.Public.Value
+	config := component.GetStill(li).Config.Home.List
+	allowPrivate := config.Private.Value
+	allowPublic := config.Public.Value
 
 	if allowPrivate == allowPublic {
 		return allowPrivate