feat(events): put calendar My-tickets filter next to the Back button

The My-tickets filter chip sat on its own row below the Back link,
wasting vertical space. Move it onto the Back-button row (still
left-aligned to clear the fixed top-right hamburger), reclaiming a row.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/modules/events/views/EventsCalendarPage.vue

@@ -42,21 +42,17 @@ function goBack() {
 
 <template>
   <div class="container mx-auto px-4 py-6 max-w-lg">
-    <!-- Back to the events feed — mirrors EventDetailPage's top-bar
-         back link for navigation consistency. -->
-    <div class="flex items-center mb-4">
+    <!-- Back to the events feed (mirrors EventDetailPage) + the
+         My-tickets filter on one row. Both left-aligned so they clear
+         the fixed top-right hamburger menu, and the filter no longer
+         takes a row to itself. -->
+    <div class="flex items-center gap-2 mb-4">
       <Button variant="ghost" size="sm" class="gap-1.5" @click="goBack">
         <ArrowLeft class="w-4 h-4" />
         {{ t('common.nav.back', 'Back') }}
       </Button>
-    </div>
-
-    <!-- Filter chip: narrows the calendar to events the user has
-         paid tickets for. Hidden when logged out — nothing to own.
-         Left-aligned so it doesn't collide with the fixed top-right
-         hamburger menu. -->
-    <div v-if="isAuthenticated" class="mb-3 flex">
       <Button
+        v-if="isAuthenticated"
         :variant="onlyMine ? 'default' : 'outline'"
         size="sm"
         class="gap-1.5"