fix(container): growth options to dynamically size Containers

examples/layouts/mixed.zig

@@ -73,8 +73,8 @@ pub fn main() !void {
         } else {
             try column.append(try App.Container.init(allocator, .{
                 .size = .{
-                    .dim = .{ .y = 5 },
-                    // .grow = .horizontal,
+                    .dim = .{ .y = 4 },
+                    .grow = .horizontal,
                 },
             }, .{}));
         }