feat(ui): add floating menu for video selection

Implement floating button that toggles a menu with video options
Add styling for floating elements and handle click interactions
Update video switching logic to prevent unintended transitions

style.css

@@ -152,6 +152,78 @@ html, body {
     text-shadow: 1px 1px 2px rgba(0,0,0,0.7);
 }
 
+/* --- 悬浮按钮和菜单 --- */
+#floating-button {
+    position: fixed;
+    bottom: 120px; /* 调整位置，使其在麦克风按钮上方 */
+    right: 30px;
+    width: 60px;
+    height: 60px;
+    background: rgba(255, 255, 255, 0.15);
+    backdrop-filter: blur(10px);
+    -webkit-backdrop-filter: blur(10px);
+    border: 1px solid rgba(255, 255, 255, 0.2);
+    border-radius: 50%;
+    display: flex;
+    justify-content: center;
+    align-items: center;
+    cursor: pointer;
+    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.2);
+    transition: transform 0.2s ease, box-shadow 0.2s ease;
+    z-index: 10;
+}
+
+#floating-button:hover {
+    transform: scale(1.1);
+    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.3);
+}
+
+#floating-button i {
+    font-size: 24px;
+    color: white;
+}
+
+#menu-container {
+    position: fixed;
+    bottom: 200px; /* 调整位置，使其在悬浮按钮上方 */
+    right: 30px;
+    width: 150px;
+    background: rgba(0, 0, 0, 0.7);
+    backdrop-filter: blur(10px);
+    -webkit-backdrop-filter: blur(10px);
+    border-radius: 10px;
+    padding: 10px;
+    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.2);
+    z-index: 9;
+    transition: opacity 0.3s ease, transform 0.3s ease;
+    transform-origin: bottom right;
+}
+
+#menu-container.hidden {
+    opacity: 0;
+    transform: scale(0.95);
+    pointer-events: none;
+}
+
+.menu-item {
+    display: block;
+    width: 100%;
+    padding: 12px;
+    background: none;
+    border: none;
+    color: white;
+    font-size: 1rem;
+    text-align: left;
+    cursor: pointer;
+    border-radius: 5px;
+    transition: background-color 0.2s ease;
+}
+
+.menu-item:hover {
+    background-color: rgba(255, 255, 255, 0.1);
+}
+
+
 /* --- 底部内容 --- */
 .bottom-bar {
     width: 100%;