IconButton name lookup does not work for all icons

When using the `IconButton` component, not all lookup names work as expected.

For example,

```

```

points to an SVG called `"dropdown-caret-down"` but the SVG in the bundle is named `"dropdown-caret-down-16"`

The result is a console warning and no icon rendered.

Start by tracing the IconButton name lookup and comparing names.DROPDOWN_CARET_DOWN with the bundled SVG name "dropdown-caret-down-16". Verify the lookup for all affected icons and confirm that the example renders without a console warning.

Written by the indexing model from the issue text.