Add event list feature (009-list-events)

Enable users to see all their saved events on the home screen, sorted
by date with upcoming events first. Key capabilities:

- EventCard with title, relative time display, and organizer/attendee
  role badge
- Sortable EventList with past-event visual distinction (faded style)
- Empty state when no events are stored
- Swipe-to-delete gesture with confirmation dialog
- Floating action button for quick event creation
- Rename router param :token → :eventToken across all views
- useRelativeTime composable (Intl.RelativeTimeFormat)
- useEventStorage: add validation, removeEvent(), reactive versioning
- Full E2E and unit test coverage for all new components

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

frontend/src/components/ConfirmDialog.vue

@@ -0,0 +1,151 @@
+<template>
+  <Teleport to="body">
+    <Transition name="confirm-dialog">
+      <div v-if="open" class="confirm-dialog__overlay" @click.self="$emit('cancel')">
+        <div
+          class="confirm-dialog"
+          role="alertdialog"
+          aria-modal="true"
+          :aria-label="title"
+          @keydown.escape="$emit('cancel')"
+        >
+          <p class="confirm-dialog__title">{{ title }}</p>
+          <p class="confirm-dialog__message">{{ message }}</p>
+          <div class="confirm-dialog__actions">
+            <button
+              ref="cancelBtn"
+              class="confirm-dialog__btn confirm-dialog__btn--cancel"
+              type="button"
+              @click="$emit('cancel')"
+            >
+              {{ cancelLabel }}
+            </button>
+            <button
+              class="confirm-dialog__btn confirm-dialog__btn--confirm"
+              type="button"
+              @click="$emit('confirm')"
+            >
+              {{ confirmLabel }}
+            </button>
+          </div>
+        </div>
+      </div>
+    </Transition>
+  </Teleport>
+</template>
+
+<script setup lang="ts">
+import { ref, watch, nextTick } from 'vue'
+
+const props = withDefaults(
+  defineProps<{
+    open: boolean
+    title?: string
+    message?: string
+    confirmLabel?: string
+    cancelLabel?: string
+  }>(),
+  {
+    title: 'Are you sure?',
+    message: '',
+    confirmLabel: 'Remove',
+    cancelLabel: 'Cancel',
+  },
+)
+
+defineEmits<{
+  confirm: []
+  cancel: []
+}>()
+
+const cancelBtn = ref<HTMLButtonElement | null>(null)
+
+watch(
+  () => props.open,
+  async (isOpen) => {
+    if (isOpen) {
+      await nextTick()
+      cancelBtn.value?.focus()
+    }
+  },
+)
+</script>
+
+<style scoped>
+.confirm-dialog__overlay {
+  position: fixed;
+  inset: 0;
+  background: rgba(0, 0, 0, 0.4);
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  z-index: 1000;
+  padding: var(--spacing-lg);
+}
+
+.confirm-dialog {
+  background: var(--color-card);
+  border-radius: var(--radius-card);
+  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.2);
+  padding: var(--spacing-xl);
+  max-width: 320px;
+  width: 100%;
+  display: flex;
+  flex-direction: column;
+  gap: var(--spacing-md);
+}
+
+.confirm-dialog__title {
+  font-size: 1.05rem;
+  font-weight: 700;
+  color: var(--color-text);
+}
+
+.confirm-dialog__message {
+  font-size: 0.9rem;
+  font-weight: 400;
+  color: #666;
+}
+
+.confirm-dialog__actions {
+  display: flex;
+  gap: var(--spacing-sm);
+  justify-content: flex-end;
+  margin-top: var(--spacing-xs);
+}
+
+.confirm-dialog__btn {
+  padding: 0.5rem 1rem;
+  border: none;
+  border-radius: var(--radius-button);
+  font-family: inherit;
+  font-size: 0.9rem;
+  font-weight: 600;
+  cursor: pointer;
+  transition: opacity 0.15s ease;
+}
+
+.confirm-dialog__btn:hover {
+  opacity: 0.85;
+}
+
+.confirm-dialog__btn--cancel {
+  background: #e8e8e8;
+  color: #555;
+}
+
+.confirm-dialog__btn--confirm {
+  background: #d32f2f;
+  color: #fff;
+}
+
+.confirm-dialog-enter-active,
+.confirm-dialog-leave-active {
+  transition: opacity 0.15s ease;
+}
+
+.confirm-dialog-enter-from,
+.confirm-dialog-leave-to {
+  opacity: 0;
+}
+</style>