ref(key): make Key struct packed and rename constants

src/element.zig

@@ -104,9 +104,9 @@ pub fn Scrollable(Event: type) type {
         fn handle(ctx: *anyopaque, event: Event) !void {
             const this: *@This() = @ptrCast(@alignCast(ctx));
             switch (event) {
+                .init => try this.container.handle(event),
                 // TODO: emit `.resize` event for the container to set the size for the scrollable `Container`
                 // - how would I determine the required or necessary `Size`?
-                .init => try this.container.handle(event),
                 .resize => |size| {
                     this.size = size;
                     // TODO: not just pass through the given size, but rather the size that is necessary for scrollable content