Stack

// ── Stack (VStack / HStack) ──
pub fn buildStack(scope: *ui.Scope, cx: *ui.Cx) anyerror!*ui.Node {
    const a = cx.allocator;
    const c = try col(cx, 16);
    try c.appendChild(a, try label(cx, "HStack gap=8"));
    const h = try W.HStack(.{ .gap = 8 }).mount(scope, cx);
    inline for (.{ "A", "B", "C" }) |t| {
        try h.appendChild(a, try W.Button(.{ .label = t, .variant = .secondary }).mount(scope, cx));
    }
    try c.appendChild(a, h);
    try c.appendChild(a, try label(cx, "VStack gap=8"));
    const v = try W.VStack(.{ .gap = 8 }).mount(scope, cx);
    inline for (.{ "First", "Second", "Third" }) |t| {
        try v.appendChild(a, try W.Tag(.{ .text = t }).mount(scope, cx));
    }
    try c.appendChild(a, v);
    return c;
}