feat: display romaji alongside kanji in Dojo mode

Closes #1

- Update /api/dojo-quiz endpoint to include romaji in the response
- Update Dojo UI to display romaji below the Kanji and above the meaning
- Add styling for the romaji text

Author: 许君山

backend/server.js

@@ -785,6 +785,7 @@ app.get('/api/dojo-quiz', (req, res) => {
         questions.push({
           verb: verbObj.kanji,
           kana: verbObj.kana,
+          romaji: verbObj.romaji,
           meaning: verbObj.meaning,
           formKey: formObj.key,
           formLabel: formObj.label,

frontend/src/App.vue

@@ -243,6 +243,7 @@
           <div class="dojo-question">
             <div class="dojo-verb">
               <span class="dojo-kanji">{{ currentQuestion.verb }}</span>
+              <span class="dojo-romaji" v-if="currentQuestion.romaji">{{ currentQuestion.romaji }}</span>
               <span class="dojo-meaning">{{ currentQuestion.meaning }}</span>
             </div>
             <div class="dojo-prompt">
@@ -1998,6 +1999,14 @@ ruby rt {
   line-height: 1.2;
 }
 
+.dojo-romaji {
+  display: block;
+  font-size: 1.2em;
+  color: #64748b;
+  font-family: monospace;
+  margin-bottom: 8px;
+}
+
 .dojo-meaning {
   display: block;
   font-size: 1.1em;