fix(frontend): use ENGINE_CONFIG instead of hardcoded engine names

- Replace ternary engine name checks in generateAudio and downloadAudio
- Use ENGINE_CONFIG[engine].name for consistent engine naming

frontend/app.js

@@ -243,7 +243,7 @@ async function generateAudio() {
                 </div>`;
             elements.audioControls.style.display = 'flex';
             elements.audioInfo.style.display = 'block';
-            elements.infoEngine.textContent = state.currentEngine === 'minimax' ? 'MiniMax' : 'CosyVoice';
+            elements.infoEngine.textContent = ENGINE_CONFIG[state.currentEngine].name;
             audioElement.src = audioUrl;
             addToHistory(text);
             showToast('音频生成成功！', 'success');
@@ -312,7 +312,7 @@ function downloadAudio() {
     if (!state.generatedAudio) return;
     
     // 文件命名规则：节目名_引擎名_日期_随机数.mp3
-    const engineName = state.currentEngine === 'minimax' ? 'MiniMax' : 'CosyVoice';
+    const engineName = ENGINE_CONFIG[state.currentEngine].name;
     const date = new Date().toISOString().slice(0, 10).replace(/-/g, '');
     const randomNum = Math.floor(Math.random() * 10000).toString().padStart(4, '0');
     const fileName = `军事科技_${engineName}_${date}_${randomNum}.mp3`;