Add organizer cancel-event flow to EventList

Organizers can now cancel events directly from the event list via the
existing PATCH /events/{eventToken} API. The confirmation dialog shows
role-differentiated messaging: "Cancel event?" with a severity warning
for organizers vs. "Remove event?" for attendees. Responses 204, 409,
and 404 all result in successful removal from the local list.

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

frontend/e2e/home-events.spec.ts

@@ -93,19 +93,30 @@ test.describe('US4: Past Events Appear Faded', () => {
 })
 
 test.describe('US3: Remove Event from List', () => {
-  test('delete icon triggers confirmation dialog, confirm removes event', async ({ page }) => {
+  test('delete icon triggers confirmation dialog, confirm removes event', async ({
+    page,
+    network,
+  }) => {
     await page.addInitScript(seedEvents([futureEvent1, futureEvent2]))
+
+    const { http, HttpResponse } = await import('msw')
+    network.use(
+      http.patch('*/api/events/:token', () => {
+        return new HttpResponse(null, { status: 204 })
+      }),
+    )
+
     await page.goto('/')
 
     // Both events visible
     await expect(page.getByText('Summer BBQ')).toBeVisible()
     await expect(page.getByText('Team Meeting')).toBeVisible()
 
-    // Click delete on Summer BBQ
+    // Click delete on Summer BBQ (organizer event)
     await page.getByRole('button', { name: /Remove Summer BBQ/ }).click()
 
-    // Confirmation dialog appears
-    await expect(page.getByText('Remove event?')).toBeVisible()
+    // Confirmation dialog appears (organizer event shows "Cancel event?")
+    await expect(page.getByText('Cancel event?')).toBeVisible()
 
     // Confirm removal
     await page.getByRole('button', { name: 'Remove', exact: true }).click()
@@ -120,13 +131,13 @@ test.describe('US3: Remove Event from List', () => {
     await page.goto('/')
 
     await page.getByRole('button', { name: /Remove Summer BBQ/ }).click()
-    await expect(page.getByText('Remove event?')).toBeVisible()
+    await expect(page.getByText('Cancel event?')).toBeVisible()
 
     // Cancel
     await page.getByRole('button', { name: 'Cancel' }).click()
 
     // Dialog gone, event still there
-    await expect(page.getByText('Remove event?')).not.toBeVisible()
+    await expect(page.getByText('Cancel event?')).not.toBeVisible()
     await expect(page.getByText('Summer BBQ')).toBeVisible()
   })
 })