- Add featured_event_id to site_settings (schema + migration)
- Backend: featured event logic in /events/next/upcoming with auto-unset when event ends
- Site settings: PUT supports featuredEventId, add PUT /featured-event for admin
- Admin events: Set as featured checkbox in editor, star toggle in list, featured badge
- Admin settings: Featured Event section with current event and remove/change links
- API: siteSettingsApi.setFeaturedEvent(), Event.isFeatured, SiteSettings.featuredEventId
- Homepage/linktree unchanged: still use getNextUpcoming (now returns featured or fallback)
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