feat(about): add monthly supporters section with 5 tiers

- Tier cards (Hostel Bunkmate through No Return Ticket) with gradient
  icons and placeholder state for empty tiers
- Animated shimmer badge and subtle radial glow behind the card
- Mobile-responsive layout, name chips show just the month on small
  screens to avoid overflow
- Copy + translations for all 15 supported languages

client/src/i18n/translations/en.ts

@@ -372,6 +372,16 @@ const en: Record<string, string | { name: string; category: string }[]> = {
   'settings.about.featureRequest': 'Feature Request',
   'settings.about.featureRequestHint': 'Suggest a new feature',
   'settings.about.wikiHint': 'Documentation & guides',
+  'settings.about.supporters.badge': 'Monthly Supporters',
+  'settings.about.supporters.title': 'Travel companions for TREK',
+  'settings.about.supporters.subtitle': "While you're planning your next route, these folks are helping plan TREK's future. Their monthly contribution goes straight into development and real hours spent — so TREK stays Open Source.",
+  'settings.about.supporters.since': 'supporter since {date}',
+  'settings.about.supporters.tierEmpty': 'Be the first',
+  'settings.about.supporter.tier.noReturnTicket': 'No Return Ticket',
+  'settings.about.supporter.tier.lostLuggageVip': 'Lost Luggage VIP',
+  'settings.about.supporter.tier.businessClassDreamer': 'Business Class Dreamer',
+  'settings.about.supporter.tier.budgetTraveller': 'Budget Traveller',
+  'settings.about.supporter.tier.hostelBunkmate': 'Hostel Bunkmate',
   'settings.about.description': 'TREK is a self-hosted travel planner that helps you organize your trips from the first idea to the last memory. Day planning, budget, packing lists, photos and much more — all in one place, on your own server.',
   'settings.about.madeWith': 'Made with',
   'settings.about.madeBy': 'by Maurice and a growing open-source community.',