Add temporal grouping to event list (Today/This Week/Next Week/Later/Past)

Group events into five temporal sections with section headers, date subheaders,
and context-aware time display (clock time for upcoming, relative for past).
Includes new useEventGrouping composable, SectionHeader and DateSubheader
components, full unit and E2E test coverage.

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

frontend/src/components/__tests__/EventList.spec.ts

@@ -1,4 +1,4 @@
-import { describe, it, expect, vi, beforeEach } from 'vitest'
+import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest'
 import { mount } from '@vue/test-utils'
 import { createRouter, createMemoryHistory } from 'vue-router'
 import EventList from '../EventList.vue'
@@ -11,10 +11,15 @@ const router = createRouter({
   ],
 })
 
+// Fixed "now": Wednesday, 2026-03-11 12:00
+const NOW = new Date(2026, 2, 11, 12, 0, 0)
+
 const mockEvents = [
-  { eventToken: 'past-1', title: 'Past Event', dateTime: '2025-01-01T10:00:00Z', expiryDate: '' },
-  { eventToken: 'future-1', title: 'Future Event', dateTime: '2027-06-15T10:00:00Z', expiryDate: '' },
-  { eventToken: 'future-2', title: 'Soon Event', dateTime: '2027-01-01T10:00:00Z', expiryDate: '' },
+  { eventToken: 'past-1', title: 'Past Event', dateTime: '2026-03-01T10:00:00', expiryDate: '' },
+  { eventToken: 'later-1', title: 'Later Event', dateTime: '2027-06-15T10:00:00', expiryDate: '' },
+  { eventToken: 'today-1', title: 'Today Event', dateTime: '2026-03-11T18:00:00', expiryDate: '' },
+  { eventToken: 'week-1', title: 'This Week Event', dateTime: '2026-03-13T10:00:00', expiryDate: '' },
+  { eventToken: 'nextweek-1', title: 'Next Week Event', dateTime: '2026-03-16T10:00:00', expiryDate: '' },
 ]
 
 vi.mock('../../composables/useEventStorage', () => ({
@@ -33,9 +38,12 @@ vi.mock('../../composables/useEventStorage', () => ({
 
 vi.mock('../../composables/useRelativeTime', () => ({
   formatRelativeTime: (dateTime: string) => {
-    if (dateTime.startsWith('2025')) return '1 year ago'
+    if (dateTime.includes('03-01')) return '10 days ago'
     if (dateTime.includes('06-15')) return 'in 1 year'
-    return 'in 10 months'
+    if (dateTime.includes('03-11')) return 'in 6 hours'
+    if (dateTime.includes('03-13')) return 'in 2 days'
+    if (dateTime.includes('03-16')) return 'in 5 days'
+    return 'sometime'
   },
 }))
 
@@ -48,32 +56,85 @@ function mountList() {
 describe('EventList', () => {
   beforeEach(() => {
     vi.useFakeTimers()
-    vi.setSystemTime(new Date('2026-03-08T12:00:00Z'))
+    vi.setSystemTime(NOW)
   })
 
-  it('renders all valid events', () => {
+  afterEach(() => {
+    vi.useRealTimers()
+  })
+
+  it('renders section headers for each non-empty section', () => {
+    const wrapper = mountList()
+    const headers = wrapper.findAll('.section-header')
+    expect(headers).toHaveLength(5)
+    expect(headers[0]!.text()).toBe('Today')
+    expect(headers[1]!.text()).toBe('This Week')
+    expect(headers[2]!.text()).toBe('Next Week')
+    expect(headers[3]!.text()).toBe('Later')
+    expect(headers[4]!.text()).toBe('Past')
+  })
+
+  it('renders events within their correct sections', () => {
+    const wrapper = mountList()
+    const sections = wrapper.findAll('.event-section')
+    expect(sections).toHaveLength(5)
+
+    expect(sections[0]!.text()).toContain('Today Event')
+    expect(sections[1]!.text()).toContain('This Week Event')
+    expect(sections[2]!.text()).toContain('Next Week Event')
+    expect(sections[3]!.text()).toContain('Later Event')
+    expect(sections[4]!.text()).toContain('Past Event')
+  })
+
+  it('renders all valid events as cards', () => {
     const wrapper = mountList()
     const cards = wrapper.findAll('.event-card')
-    expect(cards).toHaveLength(3)
-  })
-
-  it('sorts upcoming events before past events', () => {
-    const wrapper = mountList()
-    const titles = wrapper.findAll('.event-card__title').map((el) => el.text())
-    // Upcoming events first (sorted ascending), then past events
-    expect(titles[0]).toBe('Soon Event')
-    expect(titles[1]).toBe('Future Event')
-    expect(titles[2]).toBe('Past Event')
+    expect(cards).toHaveLength(5)
   })
 
   it('marks past events with isPast class', () => {
     const wrapper = mountList()
-    const cards = wrapper.findAll('.event-card')
-    expect(cards).toHaveLength(3)
-    // Last card should be past
-    expect(cards[2]!.classes()).toContain('event-card--past')
-    // First two should not be past
+    const pastSection = wrapper.findAll('.event-section')[4]!
+    const pastCards = pastSection.findAll('.event-card')
+    expect(pastCards).toHaveLength(1)
+    expect(pastCards[0]!.classes()).toContain('event-card--past')
+  })
+
+  it('does not mark non-past events with isPast class', () => {
+    const wrapper = mountList()
+    const todaySection = wrapper.findAll('.event-section')[0]!
+    const cards = todaySection.findAll('.event-card')
     expect(cards[0]!.classes()).not.toContain('event-card--past')
-    expect(cards[1]!.classes()).not.toContain('event-card--past')
+  })
+
+  it('sections have aria-label attributes', () => {
+    const wrapper = mountList()
+    const sections = wrapper.findAll('section')
+    expect(sections[0]!.attributes('aria-label')).toBe('Today')
+    expect(sections[1]!.attributes('aria-label')).toBe('This Week')
+    expect(sections[2]!.attributes('aria-label')).toBe('Next Week')
+    expect(sections[3]!.attributes('aria-label')).toBe('Later')
+    expect(sections[4]!.attributes('aria-label')).toBe('Past')
+  })
+
+  it('does not render date subheader in "Today" section', () => {
+    const wrapper = mountList()
+    const todaySection = wrapper.findAll('.event-section')[0]!
+    expect(todaySection.find('.date-subheader').exists()).toBe(false)
+  })
+
+  it('renders date subheaders in non-today sections', () => {
+    const wrapper = mountList()
+    const thisWeekSection = wrapper.findAll('.event-section')[1]!
+    expect(thisWeekSection.find('.date-subheader').exists()).toBe(true)
+
+    const nextWeekSection = wrapper.findAll('.event-section')[2]!
+    expect(nextWeekSection.find('.date-subheader').exists()).toBe(true)
+
+    const laterSection = wrapper.findAll('.event-section')[3]!
+    expect(laterSection.find('.date-subheader').exists()).toBe(true)
+
+    const pastSection = wrapper.findAll('.event-section')[4]!
+    expect(pastSection.find('.date-subheader').exists()).toBe(true)
   })
 })