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/composables/__tests__/useEventStorage.spec.ts

@@ -164,4 +164,120 @@ describe('useEventStorage', () => {
     const { getRsvp } = useEventStorage()
     expect(getRsvp('unknown')).toBeUndefined()
   })
+
+  it('removes an event by token', () => {
+    const { saveCreatedEvent, getStoredEvents, removeEvent } = useEventStorage()
+
+    saveCreatedEvent({
+      eventToken: 'event-1',
+      title: 'First',
+      dateTime: '2026-06-15T20:00:00+02:00',
+      expiryDate: '2026-07-15',
+    })
+
+    saveCreatedEvent({
+      eventToken: 'event-2',
+      title: 'Second',
+      dateTime: '2026-07-15T20:00:00+02:00',
+      expiryDate: '2026-08-15',
+    })
+
+    removeEvent('event-1')
+
+    const events = getStoredEvents()
+    expect(events).toHaveLength(1)
+    expect(events[0]!.eventToken).toBe('event-2')
+  })
+
+  it('removeEvent does nothing for unknown token', () => {
+    const { saveCreatedEvent, getStoredEvents, removeEvent } = useEventStorage()
+
+    saveCreatedEvent({
+      eventToken: 'event-1',
+      title: 'First',
+      dateTime: '2026-06-15T20:00:00+02:00',
+      expiryDate: '2026-07-15',
+    })
+
+    removeEvent('nonexistent')
+
+    expect(getStoredEvents()).toHaveLength(1)
+  })
+})
+
+describe('isValidStoredEvent', () => {
+  // Import directly since it's an exported function
+  let isValidStoredEvent: (e: unknown) => boolean
+
+  beforeEach(async () => {
+    const mod = await import('../useEventStorage')
+    isValidStoredEvent = mod.isValidStoredEvent
+  })
+
+  it('returns true for a valid event', () => {
+    expect(
+      isValidStoredEvent({
+        eventToken: 'abc-123',
+        title: 'Birthday',
+        dateTime: '2026-06-15T20:00:00+02:00',
+        expiryDate: '2026-07-15',
+      }),
+    ).toBe(true)
+  })
+
+  it('returns false for null', () => {
+    expect(isValidStoredEvent(null)).toBe(false)
+  })
+
+  it('returns false for non-object', () => {
+    expect(isValidStoredEvent('string')).toBe(false)
+  })
+
+  it('returns false when eventToken is missing', () => {
+    expect(
+      isValidStoredEvent({
+        title: 'Birthday',
+        dateTime: '2026-06-15T20:00:00+02:00',
+      }),
+    ).toBe(false)
+  })
+
+  it('returns false when eventToken is empty', () => {
+    expect(
+      isValidStoredEvent({
+        eventToken: '',
+        title: 'Birthday',
+        dateTime: '2026-06-15T20:00:00+02:00',
+      }),
+    ).toBe(false)
+  })
+
+  it('returns false when title is missing', () => {
+    expect(
+      isValidStoredEvent({
+        eventToken: 'abc-123',
+        dateTime: '2026-06-15T20:00:00+02:00',
+      }),
+    ).toBe(false)
+  })
+
+  it('returns false when dateTime is invalid', () => {
+    expect(
+      isValidStoredEvent({
+        eventToken: 'abc-123',
+        title: 'Birthday',
+        dateTime: 'not-a-date',
+      }),
+    ).toBe(false)
+  })
+
+  it('returns false when dateTime is empty', () => {
+    expect(
+      isValidStoredEvent({
+        eventToken: 'abc-123',
+        title: 'Birthday',
+        dateTime: '',
+      }),
+    ).toBe(false)
+  })
 })