feat: festival/event model frontend + topbar activeren

- Events lijst: card grid met festival/serie chips
- Festival detail: programmaonderdelen grid
- CreateSubEventDialog voor sub-events binnen festival
- EventTabsNav: breadcrumb terug naar festival
- Sessie A: festival-bewuste EventResource + children endpoint
- Topbar: zoekbalk, theme switcher, shortcuts, notificaties
- Schema v1.7 + BACKLOG.md toegevoegd
- 121 tests groen

apps/app/src/navigation/vertical/index.ts

@@ -5,7 +5,7 @@ export default [
     icon: { icon: 'tabler-smart-home' },
   },
   {
-    title: 'Events',
+    title: 'Evenementen',
     to: { name: 'events' },
     icon: { icon: 'tabler-calendar-event' },
   },