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

frontend/src/components/EmptyState.vue

@@ -1,4 +1,5 @@
 <script setup lang="ts">
+import { messages } from '../lib/messages'
 import SuggestionChips from './SuggestionChips.vue'
 
 defineProps<{ suggestions: readonly string[] }>()
@@ -7,13 +8,15 @@ defineEmits<{ pick: [suggestion: string] }>()
 
 <template>
   <div class="empty">
-    <h1>What should be playing<span class="accent"> right now?</span></h1>
+    <h1>
+      {{ messages.emptyStateHeading
+      }}<span class="accent">{{ messages.emptyStateHeadingAccent }}</span>
+    </h1>
     <p class="lede">
-      Describe the moment, not the genre. The assistant reads the request, proposes candidates,
-      verifies each one on Spotify and explains why it picked them.
+      {{ messages.emptyStateDescription }}
     </p>
     <template v-if="suggestions.length">
-      <div class="label">Try one of these</div>
+      <div class="label">{{ messages.emptyStateSuggestionLabel }}</div>
       <SuggestionChips :suggestions="suggestions" @pick="$emit('pick', $event)" />
     </template>
   </div>