Add organizer-only attendee list to event detail view (011)

New GET /events/{token}/attendees endpoint returns attendee names when
a valid organizer token is provided (403 otherwise). The frontend
conditionally renders the list below the attendee count for organizers,
silently degrading for visitors.

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

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

@@ -0,0 +1,50 @@
+import { describe, it, expect } from 'vitest'
+import { mount } from '@vue/test-utils'
+import AttendeeList from '../AttendeeList.vue'
+
+describe('AttendeeList', () => {
+  it('renders attendee names as list items', () => {
+    const wrapper = mount(AttendeeList, {
+      props: { attendees: ['Alice', 'Bob', 'Charlie'] },
+    })
+
+    const items = wrapper.findAll('.attendee-list__item')
+    expect(items).toHaveLength(3)
+    expect(items[0]!.text()).toBe('Alice')
+    expect(items[1]!.text()).toBe('Bob')
+    expect(items[2]!.text()).toBe('Charlie')
+  })
+
+  it('shows empty state message when no attendees', () => {
+    const wrapper = mount(AttendeeList, {
+      props: { attendees: [] },
+    })
+
+    expect(wrapper.find('.attendee-list__empty').text()).toBe('No attendees yet.')
+    expect(wrapper.find('.attendee-list__items').exists()).toBe(false)
+  })
+
+  it('shows plural count heading for multiple attendees', () => {
+    const wrapper = mount(AttendeeList, {
+      props: { attendees: ['Alice', 'Bob', 'Charlie', 'Diana', 'Eve'] },
+    })
+
+    expect(wrapper.find('.attendee-list__heading').text()).toBe('5 Attendees')
+  })
+
+  it('shows singular count heading for one attendee', () => {
+    const wrapper = mount(AttendeeList, {
+      props: { attendees: ['Alice'] },
+    })
+
+    expect(wrapper.find('.attendee-list__heading').text()).toBe('1 Attendee')
+  })
+
+  it('shows zero count heading for no attendees', () => {
+    const wrapper = mount(AttendeeList, {
+      props: { attendees: [] },
+    })
+
+    expect(wrapper.find('.attendee-list__heading').text()).toBe('0 Attendees')
+  })
+})