@* Session-medium fields. The hero image is resource-addressed (POST api/release/{id}/session/hero-image)
   and therefore set after the release exists — managed per-row in the Sessions browser, not at create
   time when no release id is yet assigned. This section states that contract so the admin knows where
   the hero image is managed; it carries no input of its own. *@
<MudItem xs="12">
    <MudAlert Severity="Severity.Info" Dense="true" Variant="Variant.Outlined">
        Sessions are single-track live releases. After upload, set the hero image from the
        <strong>Release Archive → Sessions</strong> browser.
    </MudAlert>
</MudItem>