19-May-2026 — base preview image URLs on the running app origin

build 651 — commit 0474a96

The previous fix injected a <base href> built from UrlService.baseUrl(). For non-local environments that returns the configured group.href (the public site address), which is not necessarily the origin the admin app is being served from - so relative image URLs still failed on the server while working locally, where baseUrl() falls back to the localhost origin.

The preview iframe needs relative image URLs to resolve to wherever the admin app currently serves its resources, so the <base href> now uses window.location.origin. Preview only; the send path is unchanged.