Add EventDetailView with loading, expired, not-found, and error states

New view fetches event via openapi-fetch, formats date/time with
Intl.DateTimeFormat. Skeleton shimmer during loading (CSS-only).
Create form now sends auto-detected timezone.
Unit tests for all five view states, E2E tests with MSW mocks.

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

frontend/e2e/event-view.spec.ts

@@ -0,0 +1,127 @@
+import { http, HttpResponse } from 'msw'
+import { test, expect } from './msw-setup'
+
+const fullEvent = {
+  eventToken: 'a1b2c3d4-e5f6-7890-abcd-ef1234567890',
+  title: 'Summer BBQ',
+  description: 'Bring your own drinks!',
+  dateTime: '2026-03-15T20:00:00+01:00',
+  timezone: 'Europe/Berlin',
+  location: 'Central Park, NYC',
+  attendeeCount: 12,
+  expired: false,
+}
+
+test.describe('US-1: View event details', () => {
+  test('displays all event fields for a valid event', async ({ page, network }) => {
+    network.use(
+      http.get('*/api/events/:token', () => {
+        return HttpResponse.json(fullEvent)
+      }),
+    )
+
+    await page.goto(`/events/${fullEvent.eventToken}`)
+
+    await expect(page.getByRole('heading', { name: 'Summer BBQ' })).toBeVisible()
+    await expect(page.getByText('Bring your own drinks!')).toBeVisible()
+    await expect(page.getByText('Central Park, NYC')).toBeVisible()
+    await expect(page.getByText('12')).toBeVisible()
+    await expect(page.getByText('Europe/Berlin')).toBeVisible()
+    await expect(page.getByText('2026')).toBeVisible()
+  })
+
+  test('does not load external resources', async ({ page, network }) => {
+    const externalRequests: string[] = []
+    page.on('request', (req) => {
+      const url = new URL(req.url())
+      if (!['localhost', '127.0.0.1'].includes(url.hostname)) {
+        externalRequests.push(req.url())
+      }
+    })
+
+    network.use(
+      http.get('*/api/events/:token', () => {
+        return HttpResponse.json(fullEvent)
+      }),
+    )
+
+    await page.goto(`/events/${fullEvent.eventToken}`)
+    await expect(page.getByRole('heading', { name: 'Summer BBQ' })).toBeVisible()
+
+    expect(externalRequests).toEqual([])
+  })
+})
+
+test.describe('US-2: View expired event', () => {
+  test('shows "event has ended" banner for expired event', async ({ page, network }) => {
+    network.use(
+      http.get('*/api/events/:token', () => {
+        return HttpResponse.json({ ...fullEvent, expired: true })
+      }),
+    )
+
+    await page.goto(`/events/${fullEvent.eventToken}`)
+
+    await expect(page.getByText('This event has ended.')).toBeVisible()
+  })
+})
+
+test.describe('US-4: Event not found', () => {
+  test('shows "event not found" for unknown token', async ({ page, network }) => {
+    network.use(
+      http.get('*/api/events/:token', () => {
+        return HttpResponse.json(
+          { type: 'urn:problem-type:event-not-found', title: 'Event Not Found', status: 404, detail: 'Event not found.' },
+          { status: 404, headers: { 'Content-Type': 'application/problem+json' } },
+        )
+      }),
+    )
+
+    await page.goto('/events/00000000-0000-0000-0000-000000000000')
+
+    await expect(page.getByText('Event not found.')).toBeVisible()
+    // No event data visible
+    await expect(page.locator('.detail__title')).not.toBeVisible()
+  })
+})
+
+test.describe('Server error', () => {
+  test('shows error message and retry button on 500', async ({ page, network }) => {
+    network.use(
+      http.get('*/api/events/:token', () => {
+        return HttpResponse.json(
+          { type: 'about:blank', title: 'Internal Server Error', status: 500, detail: 'An unexpected error occurred.' },
+          { status: 500, headers: { 'Content-Type': 'application/problem+json' } },
+        )
+      }),
+    )
+
+    await page.goto(`/events/${fullEvent.eventToken}`)
+
+    await expect(page.getByText('Something went wrong.')).toBeVisible()
+    await expect(page.getByRole('button', { name: 'Retry' })).toBeVisible()
+  })
+
+  test('retry button re-fetches the event', async ({ page, network }) => {
+    let callCount = 0
+    network.use(
+      http.get('*/api/events/:token', () => {
+        callCount++
+        if (callCount === 1) {
+          return HttpResponse.json(
+            { type: 'about:blank', title: 'Error', status: 500 },
+            { status: 500, headers: { 'Content-Type': 'application/problem+json' } },
+          )
+        }
+        return HttpResponse.json(fullEvent)
+      }),
+    )
+
+    await page.goto(`/events/${fullEvent.eventToken}`)
+    await expect(page.getByText('Something went wrong.')).toBeVisible()
+
+    await page.getByRole('button', { name: 'Retry' }).click()
+
+    await expect(page.getByRole('heading', { name: 'Summer BBQ' })).toBeVisible()
+  })
+})