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/__tests__/EventDetailView.spec.ts

@@ -22,6 +22,7 @@ vi.mock('@/composables/useEventStorage', () => ({
     getOrganizerToken: mockGetOrganizerToken,
     saveRsvp: mockSaveRsvp,
     getRsvp: mockGetRsvp,
+    removeEvent: vi.fn(),
   })),
 }))
 
@@ -30,7 +31,7 @@ function createTestRouter(_token?: string) {
     history: createMemoryHistory(),
     routes: [
       { path: '/', name: 'home', component: { template: '<div />' } },
-      { path: '/events/:token', name: 'event', component: EventDetailView },
+      { path: '/events/:eventToken', name: 'event', component: EventDetailView },
     ],
   })
 }