feat(ui): update styles and add settings dropdown

- Change progress bar gradient to pink
- Remove upload button section from HTML
- Update mic button styling with glass effect
- Add settings button and dropdown elements
- Set default video source in HTML

index.html

@@ -13,7 +13,7 @@
     <!-- 视频背景 -->
     <video autoplay muted loop id="bg-video">
         <!-- 初始可以留空，或放一个默认视频 -->
-        <source id="video-source" src="" type="video/mp4">
+        <source id="video-source" src="3D 建模图片制作.mp4" type="video/mp4">
         Your browser does not support the video tag.
     </video>
 
@@ -28,15 +28,6 @@
             </div>
         </header>
 
-        <!-- 中间区域，用于放置上传按钮 -->
-        <main class="center-content">
-            <div class="button-container">
-                <label for="video-upload" class="upload-button">更换背景</label>
-                <input type="file" id="video-upload" accept="video/*" hidden>
-                <button id="toggle-fit-button" class="upload-button">适应高度</button>
-            </div>
-        </main>
-
         <!-- 底部麦克风和链接 -->
         <footer class="bottom-bar">
             <button class="mic-button" id="mic-button" aria-label="Start Listening">