feat: 长辈模式（大字大按钮 + 偏好按账号隔离）+ 语音输入（按住说话 + 实时转写 + 后端代理 DashScope ASR + 患者端专用）+ 健康仪表盘背景渐变

backend/src/Health.Application/Speech/realtime_speech_contracts.cs

@@ -0,0 +1,10 @@
+using System.Net.WebSockets;
+
+namespace Health.Application.Speech;
+
+public interface IRealtimeSpeechRecognitionProxy
+{
+    bool IsConfigured { get; }
+
+    Task ProxyAsync(WebSocket clientSocket, CancellationToken cancellationToken);
+}