ref: move Model manipulation logic in own Element *website*

This way no `Element` that is only there for rendering requires
any internal state.

src/main.zig

@@ -29,13 +29,14 @@ pub fn main() !void {
     var renderer = zterm.Renderer.Buffered.init(allocator);
     defer renderer.deinit();
 
+    var website: Website = .init(allocator);
     var container = try App.Container.init(allocator, .{
         .layout = .{
             .padding = .horizontal(2),
             .direction = .vertical,
             .separator = .{ .enabled = true },
         },
-    }, .{});
+    }, website.element());
     defer container.deinit();
     var content_container: App.Container = undefined;
 
@@ -79,7 +80,7 @@ pub fn main() !void {
     }
     // main actual tui_website page content
     {
-        var content: Content = .init(allocator);
+        var content: Content = .{};
         content_container = try .init(allocator, .{}, content.element());
 
         var scrollable: App.Scrollable = .init(content_container, .enabled(.green, false));
@@ -185,6 +186,7 @@ const App = zterm.App(
 
 const contents = @import("content.zig");
 const Model = @import("model.zig");
+const Website = contents.Website(App);
 const Content = contents.Content(App);
 const Title = contents.Title(App);
 const InfoBanner = contents.InfoBanner(App);