feat(webrtc): 添加公共ICE服务器支持和优化HID延迟

- 重构ICE配置：将TURN配置改为统一的ICE配置，支持STUN和多TURN URL
- 添加公共ICE服务器：类似RustDesk，用户留空时使用编译时配置的公共服务器
- 优化DataChannel HID消息：使用tokio::spawn立即处理，避免依赖webrtc-rs轮询
- 添加WebRTCReady事件：客户端等待此事件后再建立连接
- 初始化时启动音频流，确保WebRTC可订阅
- 移除多余的trace/debug日志减少开销
- 更新前端配置界面支持公共ICE服务器显示

web/src/i18n/en-US.ts

@@ -283,12 +283,12 @@ export default {
     fullscreen: 'Fullscreen',
     exitFullscreen: 'Exit Fullscreen',
     screenshot: 'Screenshot',
-    reconnect: 'Reconnect',
+    reconnect: 'Refresh Page',
     noVideo: 'No video signal',
     connecting: 'Connecting...',
     streamOffline: 'Stream offline',
     connectionFailed: 'Connection Failed',
-    connectionFailedDesc: 'Unable to connect to video stream, please check device status',
+    connectionFailedDesc: 'Unable to connect to video stream, please refresh page or check device status',
     videoRestarting: 'Video stream is restarting',
     deviceSwitching: 'Switching video device...',
     configChanging: 'Applying new configuration...',
@@ -570,16 +570,18 @@ export default {
     // WebRTC / ICE
     webrtcSettings: 'WebRTC Settings',
     webrtcSettingsDesc: 'Configure STUN/TURN servers for NAT traversal',
+    usingPublicIceServers: 'Using public ICE servers',
+    publicIceServersHint: 'Leave empty to use built-in public STUN/TURN servers for NAT traversal',
     stunServer: 'STUN Server',
     stunServerPlaceholder: 'stun:stun.l.google.com:19302',
-    stunServerHint: 'STUN server for NAT traversal (e.g., stun:stun.l.google.com:19302)',
+    stunServerHint: 'Custom STUN server (leave empty to use public server)',
     turnServer: 'TURN Server',
     turnServerPlaceholder: 'turn:turn.example.com:3478',
-    turnServerHint: 'TURN relay server for restrictive networks (optional)',
+    turnServerHint: 'Custom TURN relay server (leave empty to use public server)',
     turnUsername: 'TURN Username',
     turnPassword: 'TURN Password',
     turnPasswordConfigured: 'Password already configured. Leave empty to keep current password.',
-    turnCredentialsHint: 'Credentials for TURN server authentication',
+    turnCredentialsHint: 'Credentials for TURN server authentication (only needed for custom servers)',
     iceConfigNote: 'Note: Changes require reconnecting the WebRTC session to take effect.',
   },
   virtualKeyboard: {
@@ -628,6 +630,7 @@ export default {
     absolute: 'Absolute',
     relative: 'Relative',
     connection: 'Connection',
+    channel: 'Channel',
     networkError: 'Network Error',
     disconnected: 'Disconnected',
     availability: 'Availability',
@@ -637,6 +640,7 @@ export default {
     quality: 'Quality',
     streaming: 'Streaming',
     off: 'Off',
+    defaultDevice: 'Default',
     notConnected: 'Not Connected',
     connected: 'Connected',
     image: 'Image',