fix(frontend): harden the streaming ui and extract copy and constants

frontend/src/components/ResultSet.vue

@@ -1,4 +1,5 @@
 <script setup lang="ts">
+import { messages } from '../lib/messages'
 import type { TrackEvent } from '../lib/types'
 import TrackCard from './TrackCard.vue'
 
@@ -6,7 +7,7 @@ defineProps<{ tracks: TrackEvent[] }>()
 </script>
 
 <template>
-  <div class="set" aria-label="Recommended tracks">
+  <div class="set" :aria-label="messages.resultSetRecommendedTracksLabel">
     <TrackCard v-for="event in tracks" :key="event.track.id" :event="event" />
   </div>
 </template>