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/routes/tickets.ts

@@ -25,7 +25,7 @@ const createTicketSchema = z.object({
   phone: z.string().min(6).optional().or(z.literal('')),
   preferredLanguage: z.enum(['en', 'es']).optional(),
   paymentMethod: z.enum(['bancard', 'lightning', 'cash', 'bank_transfer', 'tpago']).default('cash'),
-  ruc: z.string().regex(/^[0-9]{6,8}-[0-9]{1}$/, 'Invalid RUC format').optional(),
+  ruc: z.string().regex(/^\d{6,10}$/, 'Invalid RUC format').optional().or(z.literal('')),
   // Optional: array of attendees for multi-ticket booking
   attendees: z.array(attendeeSchema).optional(),
 });