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/components/__tests__/EventCard.spec.ts

@@ -0,0 +1,76 @@
+import { describe, it, expect } from 'vitest'
+import { mount } from '@vue/test-utils'
+import { createRouter, createMemoryHistory } from 'vue-router'
+import EventCard from '../EventCard.vue'
+
+const router = createRouter({
+  history: createMemoryHistory(),
+  routes: [
+    { path: '/', component: { template: '<div />' } },
+    { path: '/events/:eventToken', name: 'event', component: { template: '<div />' } },
+  ],
+})
+
+function mountCard(props: Record<string, unknown> = {}) {
+  return mount(EventCard, {
+    props: {
+      eventToken: 'abc-123',
+      title: 'Birthday Party',
+      relativeTime: 'in 3 days',
+      isPast: false,
+      ...props,
+    },
+    global: {
+      plugins: [router],
+    },
+  })
+}
+
+describe('EventCard', () => {
+  it('renders the event title', () => {
+    const wrapper = mountCard()
+    expect(wrapper.text()).toContain('Birthday Party')
+  })
+
+  it('renders relative time', () => {
+    const wrapper = mountCard({ relativeTime: 'yesterday' })
+    expect(wrapper.text()).toContain('yesterday')
+  })
+
+  it('links to the event detail page', () => {
+    const wrapper = mountCard({ eventToken: 'xyz-789' })
+    const link = wrapper.find('a')
+    expect(link.attributes('href')).toBe('/events/xyz-789')
+  })
+
+  it('applies past modifier class when isPast is true', () => {
+    const wrapper = mountCard({ isPast: true })
+    expect(wrapper.find('.event-card--past').exists()).toBe(true)
+  })
+
+  it('does not apply past modifier class when isPast is false', () => {
+    const wrapper = mountCard({ isPast: false })
+    expect(wrapper.find('.event-card--past').exists()).toBe(false)
+  })
+
+  it('renders organizer badge when eventRole is organizer', () => {
+    const wrapper = mountCard({ eventRole: 'organizer' })
+    expect(wrapper.text()).toContain('Organizer')
+  })
+
+  it('renders attendee badge when eventRole is attendee', () => {
+    const wrapper = mountCard({ eventRole: 'attendee' })
+    expect(wrapper.text()).toContain('Attendee')
+  })
+
+  it('renders no badge when eventRole is undefined', () => {
+    const wrapper = mountCard({ eventRole: undefined })
+    expect(wrapper.find('.event-card__badge').exists()).toBe(false)
+  })
+
+  it('emits delete event with eventToken when delete button is clicked', async () => {
+    const wrapper = mountCard({ eventToken: 'abc-123' })
+    await wrapper.find('.event-card__delete').trigger('click')
+    expect(wrapper.emitted('delete')).toEqual([['abc-123']])
+  })
+})