feat: i18n system, lang switch component, english subtitles, UI improvements, roadmap update

src/components/ChoicePanel.vue

@@ -1,6 +1,7 @@
 <script setup lang="ts">
 import { ref, watch, nextTick, computed } from 'vue'
 import type { Choice } from '@engine/types'
+import { useI18n } from '@/composables/useI18n'
 
 const props = defineProps<{
   choices: Choice[]
@@ -12,6 +13,7 @@ const emit = defineEmits<{
   choose: [index: number]
 }>()
 
+const { t } = useI18n()
 const focusIndex = ref(0)
 const btnRefs = ref<(HTMLButtonElement | null)[]>([])
 
@@ -62,7 +64,7 @@ function onKeydown(e: KeyboardEvent, index: number) {
       ></div>
       <span class="timer-text">{{ timerRemaining.toFixed(1) }}s</span>
     </div>
-    <div class="choice-prompt">做出你的选择</div>
+    <div class="choice-prompt">{{ t('ui.choose') }}</div>
     <div class="choice-list">
       <button
         v-for="(choice, index) in choices"