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/CreateEventFab.vue

@@ -0,0 +1,49 @@
+<template>
+  <RouterLink to="/create" class="fab" aria-label="Create event">
+    <span class="fab__icon" aria-hidden="true">+</span>
+  </RouterLink>
+</template>
+
+<script setup lang="ts">
+import { RouterLink } from 'vue-router'
+</script>
+
+<style scoped>
+.fab {
+  position: fixed;
+  bottom: calc(1.2rem + env(safe-area-inset-bottom));
+  right: 1.2rem;
+  width: 56px;
+  height: 56px;
+  border-radius: 50%;
+  background: var(--color-accent);
+  color: #fff;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.25);
+  text-decoration: none;
+  z-index: 100;
+  transition: transform 0.15s ease, box-shadow 0.15s ease;
+}
+
+.fab:hover {
+  transform: scale(1.08);
+  box-shadow: 0 6px 16px rgba(0, 0, 0, 0.3);
+}
+
+.fab:active {
+  transform: scale(0.95);
+}
+
+.fab:focus-visible {
+  outline: 2px solid #fff;
+  outline-offset: 3px;
+}
+
+.fab__icon {
+  font-size: 1.8rem;
+  font-weight: 300;
+  line-height: 1;
+}
+</style>