Add event list feature (009-list-events)

Enable users to see all their saved events on the home screen, sorted
by date with upcoming events first. Key capabilities:

- EventCard with title, relative time display, and organizer/attendee
  role badge
- Sortable EventList with past-event visual distinction (faded style)
- Empty state when no events are stored
- Swipe-to-delete gesture with confirmation dialog
- Floating action button for quick event creation
- Rename router param :token → :eventToken across all views
- useRelativeTime composable (Intl.RelativeTimeFormat)
- useEventStorage: add validation, removeEvent(), reactive versioning
- Full E2E and unit test coverage for all new components

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/views/EventCreateView.vue

@@ -215,7 +215,7 @@ async function handleSubmit() {
         expiryDate: data.expiryDate,
       })
 
-      router.push({ name: 'event', params: { token: data.eventToken } })
+      router.push({ name: 'event', params: { eventToken: data.eventToken } })
     }
   } catch {
     submitting.value = false