Make expiryDate an internal concern, auto-set to event date + 7 days

The expiry date is no longer user-facing: it is removed from the API
(request and response) and the frontend. The backend now automatically
calculates it as the event date plus 7 days. The expired banner and
RSVP-bar filtering by expired status are also removed from the UI,
since expiry is purely an internal data-retention mechanism.

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

frontend/e2e/event-create.spec.ts

@@ -9,7 +9,6 @@ test.describe('US-1: Create an event', () => {
 
     await expect(page.getByText('Title is required.')).toBeVisible()
     await expect(page.getByText('Date and time are required.')).toBeVisible()
-    await expect(page.getByText('Expiry date is required.')).toBeVisible()
   })
 
   test('creates an event and redirects to event detail page', async ({ page }) => {
@@ -19,7 +18,6 @@ test.describe('US-1: Create an event', () => {
     await page.getByLabel(/description/i).fill('Bring your own drinks')
     await page.getByLabel(/date/i).first().fill('2026-04-15T18:00')
     await page.getByLabel(/location/i).fill('Central Park')
-    await page.getByLabel(/expiry/i).fill('2026-06-15')
 
     await page.getByRole('button', { name: /create event/i }).click()
 
@@ -31,7 +29,6 @@ test.describe('US-1: Create an event', () => {
 
     await page.getByLabel(/title/i).fill('Summer BBQ')
     await page.getByLabel(/date/i).first().fill('2026-04-15T18:00')
-    await page.getByLabel(/expiry/i).fill('2026-06-15')
 
     await page.getByRole('button', { name: /create event/i }).click()
     await expect(page).toHaveURL(/\/events\/.+/)
@@ -59,7 +56,6 @@ test.describe('US-1: Create an event', () => {
     await page.goto('/create')
     await page.getByLabel(/title/i).fill('Test')
     await page.getByLabel(/date/i).first().fill('2026-04-15T18:00')
-    await page.getByLabel(/expiry/i).fill('2026-06-15')
 
     await page.getByRole('button', { name: /create event/i }).click()
 

frontend/e2e/event-rsvp.spec.ts

@@ -9,7 +9,6 @@ const fullEvent = {
   timezone: 'Europe/Berlin',
   location: 'Central Park, NYC',
   attendeeCount: 12,
-  expired: false,
 }
 
 test.describe('US1: RSVP submission flow', () => {
@@ -170,16 +169,4 @@ test.describe('US1: RSVP submission flow', () => {
     await expect(page.getByText("You're attending!")).not.toBeVisible()
   })
 
-  test('does not show RSVP bar on 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()
-    await expect(page.getByRole('button', { name: "I'm attending" })).not.toBeVisible()
-  })
 })

frontend/e2e/event-view.spec.ts

@@ -9,7 +9,6 @@ const fullEvent = {
   timezone: 'Europe/Berlin',
   location: 'Central Park, NYC',
   attendeeCount: 12,
-  expired: false,
 }
 
 test.describe('US-1: View event details', () => {
@@ -52,20 +51,6 @@ test.describe('US-1: View event details', () => {
   })
 })
 
-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(

frontend/e2e/home-events.spec.ts

@@ -7,7 +7,6 @@ const futureEvent1: StoredEvent = {
   eventToken: 'future-aaa',
   title: 'Summer BBQ',
   dateTime: '2027-06-15T18:00:00Z',
-  expiryDate: '2027-06-16T00:00:00Z',
   organizerToken: 'org-token-1',
 }
 
@@ -15,7 +14,6 @@ const futureEvent2: StoredEvent = {
   eventToken: 'future-bbb',
   title: 'Team Meeting',
   dateTime: '2027-01-10T09:00:00Z',
-  expiryDate: '2027-01-11T00:00:00Z',
   rsvpToken: 'rsvp-token-1',
   rsvpName: 'Alice',
 }
@@ -24,7 +22,6 @@ const pastEvent: StoredEvent = {
   eventToken: 'past-ccc',
   title: 'New Year Party',
   dateTime: '2025-01-01T00:00:00Z',
-  expiryDate: '2025-01-02T00:00:00Z',
 }
 
 function seedEvents(events: StoredEvent[]): string {
@@ -85,7 +82,6 @@ test.describe('US4: Past Events Appear Faded', () => {
           location: '',
           timezone: 'UTC',
           attendeeCount: 0,
-          expired: true,
         })
       }),
     )
@@ -199,13 +195,11 @@ test.describe('Temporal Grouping: Section Headers', () => {
       eventToken: 'today-1',
       title: 'Today Standup',
       dateTime: new Date(now.getFullYear(), now.getMonth(), now.getDate(), 18, 0, 0).toISOString(),
-      expiryDate: '',
     }
     const laterEvent: StoredEvent = {
       eventToken: 'later-1',
       title: 'Future Conference',
       dateTime: new Date(now.getFullYear() + 1, 0, 15, 10, 0, 0).toISOString(),
-      expiryDate: '',
     }
     await page.addInitScript(seedEvents([todayEvent, laterEvent, pastEvent]))
     await page.goto('/')
@@ -245,7 +239,6 @@ test.describe('Temporal Grouping: Section Headers', () => {
       eventToken: 'today-emph',
       title: 'Emphasis Test',
       dateTime: new Date(now.getFullYear(), now.getMonth(), now.getDate(), 20, 0, 0).toISOString(),
-      expiryDate: '',
     }
     await page.addInitScript(seedEvents([todayEvent]))
     await page.goto('/')
@@ -262,7 +255,6 @@ test.describe('Temporal Grouping: Date Subheaders', () => {
       eventToken: 'today-sub',
       title: 'No Subheader Test',
       dateTime: new Date(now.getFullYear(), now.getMonth(), now.getDate(), 19, 0, 0).toISOString(),
-      expiryDate: '',
     }
     await page.addInitScript(seedEvents([todayEvent]))
     await page.goto('/')
@@ -355,7 +347,6 @@ test.describe('US1: View My Events', () => {
           location: '',
           timezone: 'UTC',
           attendeeCount: 0,
-          expired: false,
         })
       }),
     )