feat: add featured event with automatic fallback

- 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)

backend/src/db/schema.ts

@@ -283,6 +283,8 @@ export const sqliteSiteSettings = sqliteTable('site_settings', {
   instagramUrl: text('instagram_url'),
   twitterUrl: text('twitter_url'),
   linkedinUrl: text('linkedin_url'),
+  // Featured event - manually promoted event shown on homepage/linktree
+  featuredEventId: text('featured_event_id').references(() => sqliteEvents.id),
   // Other settings
   maintenanceMode: integer('maintenance_mode', { mode: 'boolean' }).notNull().default(false),
   maintenanceMessage: text('maintenance_message'),
@@ -563,6 +565,8 @@ export const pgSiteSettings = pgTable('site_settings', {
   instagramUrl: varchar('instagram_url', { length: 500 }),
   twitterUrl: varchar('twitter_url', { length: 500 }),
   linkedinUrl: varchar('linkedin_url', { length: 500 }),
+  // Featured event - manually promoted event shown on homepage/linktree
+  featuredEventId: uuid('featured_event_id').references(() => pgEvents.id),
   // Other settings
   maintenanceMode: pgInteger('maintenance_mode').notNull().default(0),
   maintenanceMessage: pgText('maintenance_message'),