Extract BackLink component into App layout

Move back navigation (chevron + "fete" brand) from per-view
definitions into a shared BackLink component rendered in App.vue.
Shown on all pages except home. Hero overlay gets pointer-events:
none so the link stays clickable on the event detail page.

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

frontend/src/App.vue

@@ -1,9 +1,26 @@
 <template>
   <div class="app-container">
+    <header v-if="route.name !== 'home'" class="app-header">
+      <BackLink />
+    </header>
     <RouterView />
   </div>
 </template>
 
 <script setup lang="ts">
-import { RouterView } from 'vue-router'
+import { RouterView, useRoute } from 'vue-router'
+import BackLink from '@/components/BackLink.vue'
+
+const route = useRoute()
 </script>
+
+<style scoped>
+.app-header {
+  position: absolute;
+  top: 0;
+  left: 0;
+  right: 0;
+  z-index: 10;
+  padding-top: var(--spacing-lg);
+}
+</style>

frontend/src/components/BackLink.vue

@@ -0,0 +1,28 @@
+<template>
+  <RouterLink to="/" class="back-link" aria-label="Back to home">
+    <svg width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+      <polyline points="15 18 9 12 15 6" />
+    </svg>
+    <span class="back-link__brand">fete</span>
+  </RouterLink>
+</template>
+
+<script setup lang="ts">
+import { RouterLink } from 'vue-router'
+</script>
+
+<style scoped>
+.back-link {
+  display: inline-flex;
+  align-items: center;
+  gap: 0.15rem;
+  color: var(--color-text-on-gradient);
+  text-decoration: none;
+  line-height: 1;
+}
+
+.back-link__brand {
+  font-size: 1.3rem;
+  font-weight: 700;
+}
+</style>

frontend/src/views/EventCreateView.vue

@@ -1,9 +1,6 @@
 <template>
   <main class="create">
-    <header class="create__header">
-      <RouterLink to="/" class="create__back" aria-label="Back to home">&larr;</RouterLink>
-      <h1 class="create__title">Create</h1>
-    </header>
+    <h1 class="create__title">Create</h1>
 
     <form class="create__form" novalidate @submit.prevent="handleSubmit">
       <div class="form-group">
@@ -76,7 +73,7 @@
 
 <script setup lang="ts">
 import { reactive, ref, watch } from 'vue'
-import { RouterLink, useRouter } from 'vue-router'
+import { useRouter } from 'vue-router'
 import { api } from '@/api/client'
 import { useEventStorage } from '@/composables/useEventStorage'
 
@@ -194,20 +191,7 @@ async function handleSubmit() {
   display: flex;
   flex-direction: column;
   gap: var(--spacing-lg);
-  padding-top: var(--spacing-lg);
-}
-
-.create__header {
-  display: flex;
-  align-items: center;
-  gap: var(--spacing-sm);
-}
-
-.create__back {
-  color: var(--color-text-on-gradient);
-  font-size: 1.5rem;
-  text-decoration: none;
-  line-height: 1;
+  padding-top: calc(var(--spacing-lg) + 2.5rem);
 }
 
 .create__title {

frontend/src/views/EventDetailView.vue

@@ -8,10 +8,6 @@
         alt=""
       />
       <div class="detail__hero-overlay" />
-      <header class="detail__header">
-        <RouterLink to="/" class="detail__back" aria-label="Back to home">&larr;</RouterLink>
-        <span class="detail__brand">fete</span>
-      </header>
     </div>
 
     <div class="detail__body">
@@ -168,7 +164,7 @@
 
 <script setup lang="ts">
 import { ref, computed, onMounted } from 'vue'
-import { RouterLink, useRoute } from 'vue-router'
+import { useRoute } from 'vue-router'
 import { api } from '@/api/client'
 import { useEventStorage } from '@/composables/useEventStorage'
 import AttendeeList from '@/components/AttendeeList.vue'
@@ -437,32 +433,7 @@ onMounted(fetchEvent)
     var(--color-glass-overlay) 0%,
     transparent 50%
   );
-}
-
-.detail__header {
-  position: absolute;
-  top: 0;
-  left: 0;
-  right: 0;
-  display: flex;
-  align-items: center;
-  gap: var(--spacing-sm);
-  padding: var(--spacing-lg) var(--content-padding);
-  padding-top: env(safe-area-inset-top, var(--spacing-lg));
-  z-index: 1;
-}
-
-.detail__back {
-  color: var(--color-text-on-gradient);
-  font-size: 1.5rem;
-  text-decoration: none;
-  line-height: 1;
-}
-
-.detail__brand {
-  font-size: 1.3rem;
-  font-weight: 700;
-  color: var(--color-text-on-gradient);
+  pointer-events: none;
 }
 
 .detail__body {