fix(container/layout): padding calculation for anchor corrections

examples/container.zig

@@ -31,16 +31,15 @@ pub fn main() !void {
             .separator = .{ .enabled = false },
         },
         .layout = .{
-            .gap = 0,
             .padding = .all(5),
-            .direction = .horizontal,
+            .direction = .vertical,
         },
     });
     var box = try App.Container.init(allocator, .{
         .rectangle = .{ .fill = .blue },
         .layout = .{
             .gap = 1,
-            .direction = .vertical,
+            .direction = .horizontal,
             .padding = .vertical(1),
             .sizing = .{
                 // .width = .{ .fixed = 700 },