feat(voice-recognition): add speech recognition and emotion-based video switching

Implement voice recognition functionality that displays transcript in a styled container. Add emotion analysis to switch videos based on detected positive/negative keywords in speech. Includes UI updates for transcript display and microphone interaction.

style.css

@@ -125,6 +125,33 @@ html, body {
     /* 这个区域现在是空的，可以移除或保留以备将来使用 */
 }
 
+/* --- 语音识别结果显示 --- */
+.transcript-container {
+    position: absolute;
+    bottom: 180px; /* 放置在麦克风按钮上方 */
+    left: 50%;
+    transform: translateX(-50%);
+    width: 80%;
+    max-width: 600px;
+    padding: 15px;
+    background: rgba(0, 0, 0, 0.5);
+    border-radius: 10px;
+    text-align: center;
+    opacity: 0;
+    transition: opacity 0.3s ease-in-out;
+    pointer-events: none; /* 默认不响应鼠标事件 */
+}
+
+.transcript-container.visible {
+    opacity: 1;
+}
+
+#transcript {
+    font-size: 1.2rem;
+    color: #fff;
+    text-shadow: 1px 1px 2px rgba(0,0,0,0.7);
+}
+
 /* --- 底部内容 --- */
 .bottom-bar {
     width: 100%;